Aquarium Chemistry; Calcium, KH, GH, pH, Electrolytes, Magnesium, Mineral Ions

KH (ALKALINITY; CARBONATE HARDNESS/PH & ACID BUFFERING):

An important consideration of KH is that you can safely add the buffers (both freshwater and saltwater) that effect KH (Alkalinity) without sudden changes in chemistry, unless your freshwater KH is under 50 ppm (3 dKH) already. If your freshwater KH is under 50 ppm, pH bounces may be expected when first correcting a "too low" KH.
Once Stabilized, maintaining these KH (Alkaline) buffers keeps your tanks pH from drastic swings which can be deadly as once alkaline buffers are depleted, sudden and dangerous pH crashes are likely (see more about pH later in this article, including acid buffering).

What is Buffering, both Alkaline (KH) and Acid?

Alkalinity is the ability to resist change in pH on the measured addition of acid, meq/L (milli-equivalents per liter).
An often overlooked aspect of buffering is acidity, which is a measure of the water's ability to resist change in pH with the addition of base. Likewise, acidity should be expressed for what it is, the ability to resist change in pH with the measured addition of base, meq/L. Considered together, acidity and alkalinity constitute the buffer capacity of the water, the ability to resist change in pH from either direction.

The chemistry behind an alkaline buffer (KH) is quite complex, so I will not go into too much detail, however in the most simple terms I can think of; adding these carbonate (or bi-carbonate) buffers will raise pH to a point of stability and the continued use of certain carbonate buffer “mixes” may raise pH even more. The rise in pH is related to the ratio of H+ to OH- ions.
The CO3- will react with the H+ and eliminate it. This reaction will cause more H20 to break up into H+ and OH- ions. Because some OH- ions were already present, this shifts the ratio thereby raising pH and making the water base alkaline.

Putting it another way; KH (carbonate hardness or alkalinity) is caused by metals combined with a form of alkalinity:
KH is the capacity of water to neutralize acids and KH is made up of compounds such as carbonate, bicarbonate, hydroxide, and sometimes borate & silicate.
A higher KH can neutralize more acids produced from aquarium/pond biological processes than a lower KH.

More simply put; maintaining a certain KH does not guarantee a certain pH due to many other chemistry aspects. However maintaining a KH appropriate for the fish kept WILL prevent drastic pH swings!

In contrast, non-carbonate hardness (GH) forms when metals combine with anything other than alkalinity, which is why (despite many incorrect claims to the contrary) calcium does not raise pH directly.
Carbonate hardness (KH) is sometimes called temporary hardness because it can be removed by boiling water. GH (non-carbonate hardness) by comparison cannot be broken down by boiling the water, so it is also known as permanent hardness.

Baking Soda (Sodium Bi-Carbonate NaHCO3-), is often used for KH, Sodium Bi-Carbonate will buffer at 8.0 to 8.2. Just a little Sodium Carbonate will absorb free H+ ions, and this causes alkalinity (which is the lack of H+ ions).
To stop the Sodium Carbonate ions from consuming too much H+ and to keep a pH of 7.0 we need to restrict the amount of Baking Soda used, as it is always looking for H+ ions to consume. This is why I often prefer using products that not only contain sodium carbonates (or sodium bi carbonates), but the proper ratios of other minor elements such as Calcium and Magnesium. The use of products such as Sea Chem Buffers; Marine, Goldfish, Malawi, Victoria for marine tanks and many freshwater tanks (such as livebearer, goldfish, rift lake cichlids) is an example of my preferred methods for KH maintenance in these tanks.

Marine Buffer in particular will stabilize pH at 8.3 and no higher when used at full strength, assuming no problems with exceptional acid production such as decomposition in live rock. At lower doses it can be used in many freshwater applications.
For marine Aquariums, SeaChem Reef Builder is an excellent buffer that will over time tend to stabilize pH at 8.3
Aragonite and Seachem Cichlid Salts can also supply some carbonates as well.

Soft water or planted aquariums (or lower pH Community aquariums) are best served by SeaChem Alkaline Buffer for still important KH/pH (about 50 ppm for softwater; 100 for low KH/pH community) stability that even Discus, Bettas, etc need, as pH fluctuations caused by lack of KH buffering can be harmful to these fish as well (since the pH scale is logarithmic, please see the pH section).
I recommend countering the KH Buffer with natural Acid Buffers such as Pillow Moss, Atison’s Spa, peat, or Driftwood etc. Or chemical Acid buffers such as SeaChem Acid Buffer, as a healthy lower pH has a “balanced equation” of both acid & alkaline buffers.
Please note that the before mentioned "Natural" buffers often work very slowly as in many ways these counteract general hardness as much or more than carbonate hardness (KH).
One or more of these buffers should also be employed for softwater aquariums for correct/balanced KH/pH chemistry (see the section later in this article dealing with Amazon River, SE Asia Water).

SeaChem Alkaline Buffer is preferable and safer than baking soda, especially in planted, softwater or community aquariums where baking soda can effect mineral equilibrium in a negative way and may not maintain a stable KH.

For freshwater aquariums (& basic marine aquariums), Wonder Shells are an excellent compliment for raising Calcium, magnesium, and electrolyte levels when used with Buffers, or even Baking Soda, however by themselves Wonder Shells (or similar mineral products such as Equilibrium) do not raise KH much. Sea Chem Cichlid Salt also supplements alkaline buffers with added minerals (as well as salt), generally for use with fish such as Rift Cichlids, Livebearers, etc, but this can also be used in limited quantity with all freshwater fish.

Before I over promote Wonder Shells in this article, these can aid in proper water management, but they are not a magic bullet in any aquarium for poor aquarium husbandry such as mulm build up under gravel or decorations. However they can be one more piece of the water quality management puzzle and sometimes with fish such as Livebearers and Goldfish the results/benefits of use can be dramatic. As well a Wonder Shell only aids in KH/pH stability, they cannot fix problems with these two parameters!

I should also note that I do NOT find the use of Neutral pH regulators helpful for community aquariums.
A more natural balance of carbonate buffers and acid buffers (or a mix both natural or supplemented buffers) is much better for long term keeping of a healthy aquarium chemistry equilibrium. These products often use phosphates which are not a healthy way to neutralize pH/KH, and in fact these products drive out ESSENTIAL calcium and magnesium ions!!

If an aquarium keeper finds a neutral regulator the only way to stabilize an aquarium pH/KH, this indicates that there are likely too many acid producing organics such as mulm in canister filters (especially in ceramic media) or under gravel, decor, etc. in the aquarium. Another proof of this unnatural stability is if a Wonder Shell is used, it will produce a "dust" on the bottom that is easily stirred into a cloud in the water (due to phosphates in these products).
The bottom line is the use of Neutral Regulators such as API Proper pH 7 is not a healthy nor natural way to maintain good aquarium chemistry and my years of maintaining many 100's of aquariums has born this out!

ALKALINE (KH) BUFFERS:

Explanation of common Buffers used to raise Alkalinity (KH & eventually pH)

*Baking Soda (NaHCO3): Is essentially just Sodium bicarbonate and will raise KH, but it can easily be overdosed and does not maintain as a stable a KH or pH

*Sea Chem Marine Buffer: This is multi-ingredient product that not only raises KH and pH, but also GH as it is very balanced in its mineral balance. Due to the ingredients contained there in it will NOT raise pH past 8.3- 8.4 even when over dosed. When use in FW, small amounts should be used so as to slowly raised pH and KH as if overdosed you can raise pH to 8.3.

*SeaChem Malawi/Victoria Buffer: This is the same product as Marine Buffer and will also not raise pH past 8.4, even when overdosed (as with Marine Buffer, I have used this product for many freshwater applications such as Livebearers & Goldfish).

*SeaChem Tanganyika Buffer: again a similar product to Marine and Malawi Buffer with additional necessary mineral, however it will raise pH to 9.0 when used full strength.

*SeaChem Alkaline Buffer: This is more straight forward KH buffer that has less added minerals when these are not desired (often by planted or softwater aquarium keepers). Alkaline Buffer will continue to increase pH to 7.8 (or as high as 8.5 with correct usage), however it still is more stable and moves pH much less dramatically than baking soda making it still a much better choice in FW.
Alkaline Buffer is the preferred method (combined with Acid Buffer) for use with stabilizing Reverse Osmosis Water in lower pH/soft water aquariums. Please see the Acid/Alkaline Buffer Chart in the Low PH Buffers Section for correct ratios.

ACID BUFFERS:

Explanation of common Acid Buffers used to counter a Base (Alkalinity)

*Bisulfate salts are the preferred acid buffer for planted aquariums or for very hard water where phosphate buffers may pose an algae or cloudiness problem.

*Phosphoric Acid

*Natural Acid Buffers which often contain Tannic Acid such as; Peat, Pillow Moss (Frog Moss), most Driftwood, Indian Almond Leaves.

Tips for use of Buffers (Acid or Alkaline):

*I strongly suggest dissolving powdered buffers in warm to mildly hot water prior to addition to the aquarium. DO NOT MIX acid and alkaline buffers in the same container prior to introducing to the aquarium unless in large container such as a 5 gallon bucket meant as replacement water for a water change.
Then add this solution slowly into the tank, sometimes in cases where KH is considerably depleted; this solution should be added in increments over a couple of hours if large adjustments need to be made (such a 4dKH ppm to 8dKH).

*Always know your water source Buffering Capacity; Alkalinity (KH) prior to addition to your aquarium.

For instance if your tap or well water has a KH of 200 and your desire is to maintain a KH of 200; NO ADDITIONAL KH buffer is needed at the time of water addition/change. However with this same aquarium situation, if the KH drops between water changes, maintenance amounts of Buffers will need to be added (the amount is something you will need to determine via "trial & error" based on aquarium size and depletion rate).

*Know your aquarium:
As an example, if your KH is low (under 50 ppm) in say a Discus aquarium yet with little acid buffering; when you seek to bring up your aquarium KH for more stability, you can immediately "bounce" your pH.
Acid buffering can be from natural sources, but whether natural or added chemically, if low when you make even small changes to your KH it can move a pH.
So do NOT chase your pH, find a pH that you can keep stable with the minimum KH and stick with it, whether it be 6.8 or 7.3 (as examples).

Crushed Coral/Aragonite

Aragonite or crushed coral is sometimes employed for KH and GH stabilization, however aragonite and crushed coral (as with Wonder Shells) only aid to stabilize KH (they are poor buffers, especially crushed coral) and should not be used in place of a true KH buffer such as Sea Chem Alkaline Buffer when true buffering is necessary due to fluctuating KH or pH whatever the cause may be.

Crushed Coral is primarily made up of Calcium Carbonates (CaCO3) and has VERY LITTLE bicarbonates while Aragonite is of similar make up, but has a much better surface area for dissolving of minerals making it a better choice of the two.

Some Aragonites (that have high carbonate content) are useful at stabilizing a higher kH of around 240 ppm or more, which is the minimum KH (alkalinity) needed for Marine Aquariums, but does not respond to changes rapidly enough when carbonic acids are produced at a rapid rate in an aquarium (usually a high bio load or large amounts of organic mulm will cause this).
Even in marine aquariums with aragonite, this may not always be enough to maintain a proper KH (alkalinity) level, especially in tanks with high bio loads and without adequate water changes (even skimming can remove some elements). What Crushed Coral are somewhat better for is necessary minerals (GH) and in the case of Aragonite, it generally has a few more minerals in higher concentrations such as the important mineral (for corals), Strontium.

It often takes copious amounts of acids to free these minerals and what little bicarbonates/carbonates that are available (which is where a Calcium Reactor is helpful in marine aquariums).
For this reason, the use of crushed coral is more effective in a “Filter Bag” to release these minerals when used in Freshwater, especially African Cichlid aquaria. The use of a filter bag in a high flow area will improve the dissolution rate releasing more minerals and allowing for some buffering (as well as slightly improved adding mineral cations), although again I will point out not much carbonate (KH) buffering due to the mineral make up of crushed coral (Aragonite will do a slightly better buffering job when employed in a filter bag).

This said, despite the popular use of crushed coral for pH/KH control in African Cichlids, it is a poor choice for this, especially in high bio load aquariums due to the FACT of its mineral make up. Simply put, you CANNOT make a mineral appear out of nowhere that does not exist and that seems to be what many mistakenly believe when using crushed coral to increase KH/pH.
This is an unfortunate “aquatic myth” that many forums still perpetuate when a quick search of the chemical makeup of crushed coral would expose this folly.

The bottom line is that Crushed Coral or Wonder Shells MAY help maintain KH/pH in a low bio load aquarium, they are best used for minerals (GH) and even here Wonder Shells (or similar mineral ion supplements such as Replenish used regularly or in drip) are far superior to Crushed Coral due to the fact a Wonder Shell dissolves at a much faster rate and reacts much quicker to chemistry changes in the water than does crushed coral. As a well the use of a slow drip liquid mineral replenisher would also be superior to the use of Crushed Coral for mineral depletion.
Besides the simple mineral makeup of crushed coral, my own extensive tests show that its use to increase KH as well as GH (Calcium and other minerals) simply is poor.

References:
http://www.geosci.ipfw.edu/PhysSys/Unit_3/minerals.html
http://www.minerals.net/mineral/carbonat/aragonit/aragonit.htm

In lower pH community tanks (6.8 to 7.4) KH (Alkaline) buffers such as Sea Chem Alkaline Buffer are still important, however, as noted earlier, I like to counter these with natural lower (acid) pH “buffers” such as Indian Almond Leaves, Peat, Frog Moss, and/or Mango/Drift Wood.

Buffering your freshwater aquarium is especially important if you have plants fed by CO2 which will raise pH during peak growth times, and there is scientific evidence that GH plays a role here as well; please see this article for more about this subject: “AQUARIUM PLANTS; see PROPER NUTRIENTS ”.

For low pH/Soft Water Aquariums (such as Discus, Ram Cichlid, Betta), besides the before mentioned “slow” acid buffers (peat, Frog Moss, etc.), you can use immediate acid buffers with KH (carbonate) buffers for quicker results, such as SeaChem’s Acid Buffer.

Alkaline and Acid Buffers ratios Table, Graph

This is especially important when the use of 100% Reverse Osmosis water is employed; An Acid Buffer should be combined with an Alkaline Buffer in the ratios outlined in the chart to the left (this chart is for use with 100% RO or DI water ONLY).

Please note that these ratios are not hard and fast rules as each aquarium is very unique; so testing is 100% required and even then testing should be performed hours or even a day later to allow the chemistry to "settle". Once you establish a "sweet spot" for your unique aquarium environment, use the ratio numbers that work for you!

It is also noteworthy that these buffers only address pH and carbonate hardness and not essential mineral cations, so please read this article for a more in depth explanation of the use of RO or DI water for aquarium use:
Fish Osmoregulation; Use of RO/DI Water in Aquarium

Back to baking soda, this is an old stand by method based on the fact that baking soda does raise pH and KH, the problem is there is much new research to show that calcium, magnesium, electrolytes and Redox play a more important role in aquatic chemistry than just pH or basic KH alone (which is another reason good old fashioned water changes often help improve fish health). If Baking Soda is used, I recommend using Wonder Shells or similar products (such as SeaChem Replenish or Aragamix) to added needed calcium and other important electrolytes.

If you have a very unstable KH level (drops rapidly), look into causes such as a large amount of decomposing organic material. The more organic break down (de-nitrification), the more acids produced. Some filters if not cleaned regularly can cause this; including canister, UGF, and Wet/Dry.

Please read the sections about too low pH and KH problems, as well as the Amazon River section lower in this article for more about solutions/causes to an unstable KH.
This is especially important if you are considering using products such as pH Down or pH Up (which should never be used by an aquarium keeper that desires healthy & balanced aquarium chemistry).

For a really informative (and scientific) article about the relation of KH (Buffers) and pH, please follow this link:
pH of buffer - Henderson-Hasselbalch equation

Another interesting scientific thread dealing with KH:
http://www.thekrib.com/Plants/CO2/caco3.html

Or this excellent article:
http://www.seachem.com/Library/Articles/The_Art_and_Science_of_Aquarium_Management.pdf

GH (& MAGNESIUM):

(The section following this section deals with Calcium specifically

General hardness (GH or dGH) refers to the dissolved concentration primarily of calcium, magnesium and other mineral ions. Both Calcium and magnesium are important for proper internal osmotic processes in fish (and invertebrates).
Other ions can contribute to water hardness but are usually insignificant and difficult to measure. When fish are said to prefer “soft” or “hard” water, it is GH, not the KH that is being referred to. GH will generally not directly affect pH although "hard" water is generally alkaline due to some interaction of GH and KH (it should also be noted that GH DOES effect pH when photosynthesis is thrown into the equation, please see this article:
Planted Freshwater Aquariums).

Although many aquarists worry about “too high GH” (based on respiration problems), this is based on long ago proven false myths. In reality freshwater generally would take a GH of over 500 ppm to cause this problem. More importantly as to respiration the surface epithelia of gills and body surfaces are protected from direct interaction with the environment by mucous and intercellular junctions. Fish mucous has been postulated to have calcium binding properties. Mucous is a glycoprotein and could serve as a calcium chelating agent retarding ion loss from epithelial cells as a charged surface coat or barrier and thus is dependent on calcium for normal function. Intercellular junctions are specialized areas of attachment between epithelial cells preventing the loss of ions and fluids from the membrane which bathes and surrounds the cells beneath.

GH is an area of aquarium chemistry where there is a lot of misunderstanding or simply down right wrong advice. I have received many calls, emails, etc. over the years asking what do about their so-called high GH. Often this GH turns out to be around 200-300 ppm which is fine for most fish (low for African Cichlids, livebearers and even goldfish do better at higher GH).
This is based on old assumptions of respiration in fish, as well as lack of understanding of the importance of positive Calcium ions (as well as Magnesium & Potassium) in the regulation of MANY bio processes in fish including healing, heart function, and regulation of osmotic functions. GH even plays a role in pH control in planted aquariums (similar processes in marine aquariums, which is why the popularity of Kalkwasser, although GH is not referred to in Marine Aquariums, usually separate Calcium and other tests are performed). I recommend reading the section, “Calcium Carbonate” which explains more about Calcium as well as many of the outside links/references.

This misunderstanding of GH also flies in the face of the best research to date about the importance of Redox in aquarium health and since Calcium and Magnesium play a role in a balanced Redox (as can UVC Sterilization), understanding that you may have a high GH, YET your aquariums Calcium or other Redox reducers may have given up all possible positive charges (cations) to cells (or other bio processes) under oxidation.
It is for this reason, then, that calcium and magnesium supplies MUST be constantly renewed; without this “fresh” calcium, etc. your Redox balance and of coarse fish (or other aquatic inhabitants such as coral, frogs, shrimp) will suffer!

It is also noteworthy that a GH test is not always an accurate measure of positive calcium and other mineral ions (cations), as with many Ammonia test kits, which are inaccurate after using products such as Prime and give false positive for ammonia NH3 as they cannot discern the difference between the NH3 and NH4+.
The same can be said for GH tests that may show a high GH when in reality all positive calcium ions are depleted due to Redox balancing, which is why one MUST constantly supply these mineral cations by whatever means, whether by regular water changes (which often are not enough, especially in small aquariums) or by use of mineral replenishers such as Wonder Shells (which will throw off accurate readings of GH test kits due to their constant supply of positive mineral ions such as calcium!!!).

Examples of GH and Important mineral Ions in an Aquarium/Pond:

Depletion of Positive Ions
Think of it this way; a storage battery "works" only when a positive and a negative electrode are present to maintain an electrical current. When the positive ion charged plates become exhausted, the battery is no longer any good until recharged. In a lead/acid batteries essentially lead (Pb) and lead oxide (PbO2) are changed to lead(II) sulfate (PbSO) in the discharged state, However lead is still present (as with calcium in an aquarium) in a discharged state.

Water changes and additional supplements are generally necessary to replenish these mineral ions (cations). Using the car battery as an example again, when re-charging, a 12 volt battery will show a charge of up to 14 volts in a 12 volt battery shortly after and at the completion of a charge, this is similar to the high GH (often over 400) with the use of many methods of adding mineral electrolytes such as Aragomix or Wonder Shells.

Increasing GH Readings as per Tests
Often when an aquarium keeper only “tops off” for evaporation or performs inadequate/small water changes the GH may actually climb in areas of hard water.
This does not indicate a healthy aquarium, rather quite the opposite as the small amount of mineral ions that are added via “top offs” or small water changes will not keep up with depletion even though your GH test shows a climbing GH (General Hardness).
Using the auto/RV battery example again; simply throwing more lead into your battery may increase lead content, but does not necessarily increase the electrical charge.

The bottom line is adequate water changes often along with mineral supplements are required to keep healthy ionization in your aquarium/pond and a stable GH is an indicator of this, not a climbing GH (although many supplements will increase GH until water changes).
See this article for more on this subject:
Redox Balance in Aquariums

Further GH Suggestions

Products such as Wonder Shells, similar mineral blocks, or powders such as AragaMight are excellent for mineral cation (GH) maintenance.
As well the use of aragonite in filters can also be employed for mineral cation maintenance although my experience has shown the method of using aragonite to be less responsive to rapid changes in positive mineral ion needs in FW (especially planted aquariums) than the use of Mineral Blocks or drip methods.

Mineral Blocks such as Wonder Shells that dissolve slowly and thus keep a more balanced positive mineral ion level are the best method from my experience, however powders such as AragaMight (by CaribSea) can be pre-dissolved and then dripped slowly from 2 liter bottle (or similar) using air line tubing and an airline control valve to aid in a slow drip are a good alternative (more so for larger tanks as most drip rates would be too rapid for small tanks). Another product that can be used for this process is SeaChem Replenish mixed into a volume of water and then dripped into the aquarium (this is an excellent product for Amazon River tanks).

SeaChem Cichlid Salt also has essential minerals and buffers in the CORRECT rations based on the amount of slat one would add to most freshwater applications; HOWEVER products such as API Aquarium Salt only has ratios that would require enough salt added to a nearly a saltwater aquarium to achieve essential minerals for most freshwater applications (especially cichlids and livebearers), making this product (API Aquarium Salt) an extremely poor choice for mineral replenishment.

Finally the obvious way to replace minerals (electrolytes/cations) is via regular water changes (with water that contains minerals, not un-replenished RO Water), however with high bio load aquariums or high mineral need aquariums such as Molly or other livebearer tanks, water changes may not be adequate. As my tests (especially those conducted in the 1990s) show that a constant supply of these mineral improved disease resistance.
See: “A Healthy Aquarium; Disease Prevention”

It should also be noted that your GH may be artificially high from the use of mineral blocks/powders such as Wonder Shells, however much of this is Calcium of which most all fish (fresh and saltwater as well as invertebrates) can tolerate in high levels.

MAGNESIUM

Magnesium is important for proper osmotic functions in fish and invertebrates. Magnesium is essential for Calcium assimilation, so when magnesium levels are low, the calcium supply becomes exhausted. For this reason, Magnesium is better added in the proper balance with calcium (which both are essential to each other for proper utilization), in such products as Wonder Shells or aragonite sand in a small bag in the filter (although the later is not as reliable).
Magnesium should be part of your overall mineral balance in your aquarium and kept at a level of 1200 to 1400 ppm in marine aquariums (lower for freshwater).

Epsom salts that contain magnesium sulfate, are best used for therapeutic reasons such as to aid in flushing the system as it aids in and speeds osmotic function, and helps to move fluids out of the body. Sulfates, one of the major components of Epsom Salt, have been shown effective in improving nutrient absorption and toxin elimination. Magnesium, the other major component of Epsom Salt, plays a role in the activity of more than 325 enzymes.
That said you would only want to add about 1/4- 1/2 teaspoon per 5 gallons (18 liters). Although useful for therapeutic reasons, magnesium and sulfates in particular are best introduced as part of a greater trace element balance in an aquarium. I ONLY recommend Epsom Salts for therapeutic aquarium treatment. Also note that Epsom salts (as well as sodium chloride; regular table salt) do NOT evaporate or decompose like antibiotics, so only add more after water changes.

Other needs for Magnesium:
• Normal calcium balance in organs
• Healthy muscles
• Healthy nerve transduction
• Healthy calcium balance in blood vessels

References:
http://www.mgwater.com/rod06.shtml

CALCIUM CARBONATE:

Calcium carbonate in your aquarium will keep a more stable electrolyte balance (for osmotic function), while magnesium is another important element that works with calcium.
A proper amount of Calcium and Magnesium in your aquarium will affect the fish health positively, including fish such as Discus, German Rams and Apistos (see Amazon River Section for more as to the use of calcium with soft water fish)!!!

Magnesium and calcium have been shown to increase resistance to degenerate diseases by lowering the acidity in the body. This will help with prevention of ich, fungus, and general “wear and tear” in your fish. Calcium also helps in healing and stress, and without proper calcium levels healing may be difficult or impossible. Calcium is also important and has been shown to both prevent and treat Hole in the Head disease common to cichlids (also referred to as HITH).
The addition of antibiotics (such as Tetracycline) will lower calcium absorption, while the presence of correct amounts of calcium in the aquarium water will considerable reduce the toxic side effects of Malachite Green which is why a GH (for freshwater calcium measurement) of at least 100 ppm or higher is SO VERY important to ich treatment.

In fact I will go a step further as need for Calcium (even in freshwater) seems to be totally misunderstood (I have observed this quite a lot in both scientific and non-scientific observations over the years!).
Here is an important quote:
“The presence of free (ionic) calcium at relatively high concentrations in culture water helps reduce the loss of other salts (e.g. sodium and potassium) from fish body fluids (i.e. blood). Sodium and potassium are the most important salts in fish blood and are critical for normal heart, nerve and muscle function. In low calcium water, fish can lose (leak) substantial quantities of these salts into the water.”
See reference below;
Understanding Water Hardness.

In freshwater aquariums I recommend a minimum of 100 ppm of calcium (which a GH of 100+ ppm will generally provide).
Please also read this article from Aquarium Answers as well, as much of what is contained in this article relates to the importance of Calcium and other minerals as well:
Proper Osmotic function, Do Fish Drink?

Another note about calcium; Calcium is very important to proper discus health, yet calcium can adversely affect the kH of a discus aquarium when combined with sodium carbonates or bi carbonates, which is generally kept at a pH below 6.5.
I have successfully used sources of calcium such as Wonder Shells, in discus aquariums by using a mix of RO (Reverse Osmosis) water and tap water (dilution will vary depending on your tap and tank water parameters). I then add electrolytes to the RO water and add peat to the filters. I have used this method successfully with discus and added the needed calcium with no pH climb.

Calcium is also a major Reducer with a negative 2.87 electron reduction rating, and plays an important role in maintaining a healthy aquarium Redox Balance that is a VERY important aspect of true water quality.

Finally, back to the aspect of Calcium (& magnesium) in general is if these important elements are in “short supply” besides the before mentioned problems, an aquarist may also see pH swings a few hours after the lights go on as the process of Photosynthesis in algae will increase pH during daylight hours if low levels of calcium and magnesium are present (as noted earlier in the GH section as per studies). Keep in mind that a pH swing from 7.8 to 8.2 (as is common in this situation) is four fold increase in pH since the pH scale is logarithmic.

Other needs for calcium:

• Calcium is a vital component in blood clotting systems and also helps in wound healing.
• Calcium helps to control nerve transmission, and release of neurotransmitters.
• Calcium is an essential component in the production of enzymes and hormones that regulate digestion, energy, and fat metabolism.
• Calcium helps to transport ions (electrically charged particles) across the membrane.
• Calcium is essential for muscle contraction.
• Calcium assists in maintaining all cells and connective tissues in the body.

For further reading about Calcium and other minerals, please reference these articles:

This one is great:
Understanding Water Hardness

A very well informed forum post:
Calcium and Osmoregulation

For relationship of mineral bio-availability when positive and negative ions are considered:
http://www.bradfieldorganics.com/soilbasics3.html

For more information about how Calcium, pH, GH, and KH relates to ponds, please see this article about Ponds:
A Clear Pond; Pond Information

Calcium, Kalkwasser, Reactors, Magnesium in Marine Aquariums

Your Calcium level should be a minimum of 400 ppm for marine. For saltwater aquariums, I recommend Reef Calcium; polygluconate along with the use of aragonite sand or crushed coral for calcium level maintenance (Calcium Generators also work well for advanced aquarists).
Although Kalkwasser is popular among many advanced marine aquarists, caution should be used with this method of adding calcium to your marine aquarium (this is not to say Kalkwasser does not work, in fact introduced properly it is an excellent way to regulate calcium and alkalinity in saltwater aquariums).

Here is how Kalkwasser works:
Used properly Kalkwasser (Calcium Hydroxide) is slowly dripped into your aquarium, it captures free Carbon Dioxide present in the tank water and converts it to Bicarbonate ions.
However if you drip too fast or if there is not enough Carbon Dioxide available in the water, Carbonate ions will be formed which will make the Ca++ you are trying to add to your tank get wasted by the useless precipitation of Calcium Carbonate (often forming a white residue that precipitates out of your aquarium). Too rapid addition of Kalkwasser may actually cause the Calcium and Alkalinity in your tank to go down instead of up. See the equation below:
Ca++ + 2(HCO3-) + Ca++ + 2(OH-) <==> 2 CaCO3 + 2 H2O

Often even a slow drip of Kalkwasser (Calcium Hydroxide) can cause the above reaction if there is not enough CO2 present in your marine aquarium. One method to avoid this is to add 15ml of 5% Distilled White Vinegar (Acetic Acid) into a 1 liter or 1 quart container.
Dissolve 1/2 teaspoon of Kalkwasser into the Acetic Acid, and then dilute to 1 liter (1 quart) volume with either RO/DI water (tank water can be used in a pinch).

Calcium Reactors for Reef Tanks:
As noted earlier in the Kalkwasser section, a Calcium Generator/Reactor is an excellent idea for maintenance of calcium and alkalinity as well as KH/pH regulation, especially in marine/reef tanks heavily stocked with stony corals. A calcium Reactor works by providing a steady stream of calcium by using CO2 in the reactor. Although I have not had an instance where this was an "essential" item for my reef tanks, it can be very useful for previously noted reasons.
Under normal circumstances/conditions a Fluidized Filter utilizing Oolitic sand media can accomplish similar results, however for high bio load reef tanks with large amounts of stony corals, a Calcium Reactor will produce more calcium.

The advantage is similar to the simple Wonder Shells in freshwater (except better in my opinion); it provides an essential positive calcium ions, that are often exhausted , even when tests show calcium still present in the aquarium (See the section in red font in the GH section of this article).

About Plaster of Paris or Tums for Calcium (also Lime):

Although long ago discredited, Plaster of Paris is often recommended as a source of calcium for ponds or aquariums in place of aragonite, Wonder Shells or similar, this is NOT a substitute for Wonder Shells aragonite or similar and is not the same!
Plaster of Paris is a poor choice for GH or Calcium as Calcium needs to be in the proper ratios with other elements such as Magnesium to be utilized by aquatic life (such as osmotic function).
Lime is also similarly recommended for ponds for KH, GH and pH, however it is simply CaO and does not contains other elements necessary including bi-carbonates and magnesium to name but a few.

"Tums" are one more urban myth product recommended for GH & KH, but again this is only Calcium Carbonate and does not provide the completer minerals necessary for mineral ion replenishment nor ANY KH buffering!

Here is a list of ingredients of Plaster of Paris:

*CaSO4 , 1/2H2O: 97.97%
* SiO: 0.94%
* Al2O3: 0.69%
* Fe2O3: 0.28%
* MgO : 00.12%

For a further explanation of Plaster of Paris in aquariums and Ponds, please read this article:
THE DIFFERENCE BETWEEN PLASTER OF PARIS AND PRODUCTS SUCH AS WONDER SHELLS

ELECTROLYTES;

This section is somewhat redundant, as the previous section mentions Calcium and Magnesium.
These along potassium and Sodium make up essential “Reducing Electrolytes” while Chloride and Phosphates are generally oxidizing electrolytes (PO4; is an oxidizing agent but a very poor one). Generally Calcium and Magnesium are associated with hard water while Sodium, Potassium, and Phosphates are associated with soft water.

What are Electrolytes?
Electrolytes are molecular substances containing free ions which behave as an electrically conductive medium. In fish (or other living things) the primary ions of electrolytes are sodium (Na+), potassium (K+), calcium (Ca++), magnesium (Mg++), chloride (Cl-), phosphate (PO4---), and hydrogen carbonate (HCO3-).
Fish and other aquatic life forms such as shrimp require a subtle and complex electrolyte balance between the intracellular (inside the cell) and extra cellular (outside the cell such as plasma membranes) environment. In particular, the maintenance of precise osmotic gradients of electrolytes is important. These gradients affect and regulate the hydration of the fish, blood pH, and disease resistance and are important for proper nerve and muscle function.

Sudden changes in these electrolytes (as with pH) can be stressful/detrimental as well, this includes rapid positive changes. For this reason any aquarium that is depleted of positive mineral ions in particular, should have these introduced slowly.
This is especially the case with many Labyrinth fish (such as Bettas), and Crystal Red Shrimp even though both benefit greatly from these mineral cations.
A fish or invertebrate stressed by the introduction of necessary positive ions is not evidence that these cations should avoided, rather proof of an unhealthy mineral cation depleted environment (as per scientific reasoning). To avoid this stress, I would suggest a 1/4 to 1/2 dose of Replenish, Wonder Shells, etc. if kept in a previously ion depleted environment.

Salt is another type of electrolyte commonly used in a dose of one tablespoon per 5 gallons (20 liters) in freshwater aquariums. This is one way to add some sodium electrolytes to a freshwater aquarium, but this should not be the only.
Please Read this article prior to using salt in a freshwater aquarium: Salt use in Freshwater Aquariums

Do NOT make the mistake with a freshwater aquarium of using home softener water, as this is creates water totally out of balance with essential electrolytes.
The salt used produces water vastly too high in sodium and this high sodium water will precipitate out ESSENTIAL positive calcium ions. Adding these minerals back in via Replenish, Wonder Shells, Oolitic sands, etc. will not correct this long term at all. If Home water softener water is used, it must slowly be changed out.
See: Home/Office Water Softeners for Fish

Products such as SeaChem Replenish adds essential Electrolytes, more so in the “soft” electrolytes and in more trace amounts. Wonder Shells also electrolytes (especially the essential Redox Reducing “Hard” electrolytes). The advantage of mineral blocks such as the slow dissolving Wonder Shells is these electrolytes are added over more longer sustained periods (important for mineral cation depletion) and even though more “hard” are still quite useful if only in half doses for more soft water fish such as Bettas, especially when combined with natural “long term softeners such as Indian Almond Leaves, Peat, Driftwood, etc.)

Salt will also aid in disease prevention as it will help with the generation of the slime coat (or Mucous) on fish as salt acts on the osmotic gradient. But care needs to be given with salt sensitive fish such as catfish not to exceed this amount. Another aspect of salt is that although it aids in the prevention and even treatment of Freshwater Ich (Ichthyophthirius multifilis), it is often poor treatment for a full blown infection.

The importance of electrolytes/trace elements in Marine aquariums is magnified since most marine (saltwater) drink the water around them. Depletion of these trace elements through biological processes needs to be compensated for by water changes using a quality marine mix AND by testing your alkalinity (KH)/Calcium/Magnesium and adding buffers such as Sea Chem Buffer accordingly that not only add necessary carbonates for buffering but also add necessary electrolytes such as Chloride, Calcium, and Magnesium to name a few.

For MUCH more on the effects of electrolytes and their function in freshwater and saltwater:
How do Fish Drink; Proper Osmotic Function

Further Reading/references about the importance of Electrolytes in all organisms (including fish and humans)
http://www.umm.edu/ency/article/002350.htm
http://www.traceminerals.com/electrolytes.html
http://faculty.weber.edu/jkelly/2230%20fluids%20and%20electrolytes.htm

PH:

PH is unfortunately often an area of misinformation with too much importance is give to “exact” pH numbers. As well unstable pH numbers often indicate other issues such as high amounts of decomposing organic mulm/high DOC.

Often aquarists will “chase” pH trying to achieve the “perfect” pH not realizing that pH stability is generally far more important than the actual pH number. Fish can adapt to different pH, however fish are NOT tolerant to wide swings in pH.
There is a simple explanation to this that many are not aware of, that is the pH scale is logarithmic, meaning a change of pH from say 7.0 to 6.0 is a ten fold increase in acidity, while a change from 7.0 to 5.0 is 100 times change in acidity (it also goes the other direction as to alkalinity).

This is also why large water changes (25% +) are generally a good idea unless pH (and GH) levels are not changed (this also why cleaning filters such as the Eheim Sludge Remover are useful for tanks with high bio loads that may require larger water changes). This is also an important reason to not only float your new fish for temperature adjustment, but to also slowly introduce aquarium water to your new fish’ shipping bag prior to tank introduction.

Reference: Elmhurst Education; pH
Diagram above from: The Green Lane (http://www.ns.ec.gc.ca/)

KH as noted earlier is a stabilizer of pH (towards the alkaline side) whereas peat, Aquarium Drift Wood , Pillow Moss, and dried almond leaves (such as Bio Lif) will aid in lower stabilization. As well, for really troublesome high pH aquariums, cutting pH/KH with blended RO water may be necessary (see later in this article).
Please note that Natural Buffers such as Peat, Driftwood, etc. with the exception of Pillow Moss generally lower pH via a slow release of acids such as Tannins. If your carbonates are high (KH) your pH will remain high until a slow balance is reached (please read more about this in the Amazon River Water section). To reach an acid/carbonate balance more quickly, products such as SeaChem’s Acid Buffer can be used.

If using Indian Almond Leaves, Pillow Moss, or Peat, I suggest at least temporarily suspending the use of carbon, you can still use it, just not after initial use of these natural acid buffers, as Carbon can remove Tannins. If the water gets too brown from these products, then slowly re-introduce the carbon back in.

More in Depth pH Information:

The main point I would like to make as to pH is that often too much concern is given to a perfect pH when in reality a stable pH is more important, which I can speak to in the 1000s of aquariums I have maintained at different pH and other parameters.
As an example, I have seen Discus (a fish which comes from waters often under 6.5) breed in aquariums with a pH of 7.5.
What is stressful is a pH that is not stable therefore a good KH and/or acid buffer is important. What I have found FAR MORE IMPORTANT is electrolytes and calcium (which will also affect a good Redox Potential) present than a so called perfect pH.

The discus under my care were much more healthy with a KH of around 50 ppm, a GH around 100-200 ppm (& even higher), and a Redox Potential around +125 to -200 mV than with a pH of 6.5- 7.0 (please note that these numbers just given are for discus, for many fish such as livebearers I kept a much higher KH and GH).
Ditto goes for Bettas, which are fish I probably read more incorrect information about than any as to what is important to these fish as per water chemistry (GH, KH, pH, & Redox in particular).

Another point to pH is tap water or well water pH when drawn will often gas out (sometimes referred to as “gassing out”).
This is trapped CO2 gas in the tap water (also Hydrogen Sulfite as well) that will slowly gas out of the water if allowed to sit.
What I mean is you will get a sample of tap/well water then immediately test it and get a result such as 6.5 that can rise to 7.0 or higher over the next hour as CO2 gasses out, assuming there are carbonates (KH) in the water (even more common in well water from my experience).
This is noteworthy in testing your tap water as you will NOT get accurate tap water pH readings if you test your water immediately after drawing it from the tap, it is best to wait at least one hour. This gassing out does NOT affect GH or KH as these are minerals that remain in the water.

The addition of mineral blocks such as Wonder Shells would not cause a problem as these would not add more carbonates to water already containing carbonates at level of 150 ppm KH for example. Again, stability is the key point and adding phosphate containing pH lowering products (such as “pH Down”) will tend to cause roller coaster pH swings in an established tank.

Better is a stable GH and KH with the addition of Bio Lif, Peat, Driftwood, and possibly Aquarium Drift Wood , Frog Moss. The use of an Acid Buffer along with carbonate (KH) buffers during initial set-up or water changes can provide more immediate results for low pH stability.
Assuming a constant supply of carbonates (KH), the use of the above mentioned slow and “fast” acid buffers can also provide essential CO2 for planted aquariums.

Finally, another point that should be made as per pH that every aquarium keeper should be aware of is at a pH of 6.0 most all nitrification ceases (conversion by nitrifying bacteria of ammonia and nitrites), while on the other side of the equation most non-toxic ammonium (NH4) converts to toxic ammonia (NH3) at a pH of 8.0.
The use of products such as SeaChem Stability which uses facultative bacteria that can still "eat" wastes at lower pH of 6.5 or less where nitrification starts to slow substantially. SeaChem Prime would be a good product to bind ammonia (NH3) at a higher pH (such as 7.5 or higher) until nitrification can "catch up".
See: Aquarium Nitrogen Cycle

Here (below) is an interesting chart and calculator for the relationship between KH and pH as it relates to CO2 in planted aquariums:
Measuring CO2 levels in a Planted Tank

Too LOW pH or KH problems Corrections for Unstable KH; Raising pH:

First start by testing your tap or well water (as stated earlier this can gas out so wait for 1 hour before testing).
If your tap/well water is low in pH with little buffering KH, you will have problems maintaining stable or higher pH if that is desired. Areas that draw their water from rivers, especially that flow in boggy areas or are of volcanic origin may have very low pH/KH.
If tap/well water is the problem or part of the problem you will need to add a buffer.

A complete buffer such as Sea Chem Buffer (Marine OR Freshwater) will work well as this supplies ALL elements necessary and much more steadily than Baking Soda or crushed coral/aragonite.
For planted aquariums I prefer the Sea Chem Alkaline Buffer, although this product is not as stable as marine or rift lakes buffer as this buffer is more basic like Baking Soda so regular checks of KH are more important when this buffer is employed.

However, as noted in the KH section, the use of phosphate based products such as neutral regulator SHOULD BE AVOIDED!

While Wonder shells will help with Calcium, GH, & positive mineral ions; these are NOT a solution to a unstable pH/KH. At best these only aid in KH maintenance, however they are not as useful for water that is already very low in KH/pH and needs to be brought up.

As noted in the KH section, when a buffer is added to an aquarium with a KH below 50-100, while at the same time there are little acid buffers (either natural or chemical), the pH may bounce.
DO NOT Chase the pH, simply add some form of acid buffer (many are described later too) and/or accept your new pH.
A tank with stable pH of 7.3 and KH of 50-80 for a Betta is better than one with a KH of under 50 and pH of 6.8!!

If the tap/well water is OK or adjusted to preferred KH/pH yet continues to drop rapidly, I would look at tank conditions.
Here are a few possible problems that cause pH/KH drops to look into: (Please note that these problems are often interrelated):

*Too high of DOC (dissolved organic compounds) caused by organic debris/mulm, high fish loads, etc.
This can be spotted by a KH of (for example) that starts out at 80 ppm after cleaning, addition of buffer, and/or correct out of the tap, however KH drops rapidly after the initial measurements. As well, another symptom is that often ammonia, nitrites, and eventually nitrates will spike or be unstable.

Increasing the frequency of filter media rinsings (in cool de-chlorinated water though, so as to preserve nitrifying bacteria). This may mean rinsing as often as twice a week and this includes filter media inside bio bags (Whisper), carbon inserts (Aqua Clear, Internal Wet/Dry), etc.
Also increasing the amount of buffers added to maintain a stable KH will help (assuming ammonia spikes do not indicate a more serious issue).

Lowering fish levels or other aquarium animal inhabitant populations will most certainly help. As well, watch for snail population "explosions", especially small snails living in filters, under gravel, etc. as these can be a hidden cause of acid producing nitrification and decomposition.

*Mulm buildup under rocks/décor and in canister filters/ Wet-Dry filters. Canister filters in particular if let go without a cleaning more than 6 weeks can buildup a lot of decomposing mulm that will add acids to your water.
The use of SeaChem Purigen can absorb organic compounds prior nitrification and/or decomposition. As well SeaChem Matrix added to filters can balance the nitrification process with de-nitrification.

*Too much Driftwood/Mango Wood; Some driftwood in particular can be full of tannins that will lower pH/KH.
Also decomposing (rotting) driftwood will lower pH and KH more than normal cured driftwood, often a symptom of this besides pH drops includes ammonia, nitrite and eventually nitrate spikes.

*Too deep a sand bed, this again can add to decomposition that leads to acid build up (sand tends to worse than gravel here, however gravel can cause this too when too deep.
Even an otherwise normally good #3 grade of gravel that is regularly vacuumed may still harbor organic mulm, this is particularly true of many epoxy coated colored gravels as this coating often starts to loosen and allow organic mulm to be trapped there resulting in rapid KH depletion!
The solution is to often remove ½ the gravel at a time (so as to cause as little interruption of the nitrogen cycle) and either change (usually in the case of colored gravel) or thoroughly wash it.

*Infrequent or poorly conducted water changes/cleanings.
Please see this article for more: “Aquarium Cleaning; Methods & Reasons”

After correcting these problems, you still may need to add a buffer or aragonite bag to your aquarium.

Lowering High pH for Any Aquarium

Also; Providing Amazon/SE Asia River/West Africa Water
For Fish such as Discus, Bettas, German Rams, Apistos (Apistogrammas)

For areas with high KH or pH problems the use of RO or DI water blended with tap or well water is simple and effective method to solve this "problem" (combined with pH/KH buffers discussed later).

Do NOT use products such as pH down. Simply adding sodium bisulphate (HCl) will lower the pH, but will not keep a stable pH for which stability is much more important than the actual pH number for most fish.

RO (Reverse Osmosis) or DI (De-ionized) water can be used to aid in pH, GH, & KH reduction.
The process of blending RO with tap or well water is also called "Cutting Water".
Other than advanced aquarium keepers, I would recommend using no more than 25% to start with the remaining 75% well or tap water. If your tap water is say 8.0 pH with a KH of 200 ppm, the addition of 25% RO or DI water (neutral 7.0 ph, 0 KH) should cut your KH by 25% to 150 KH, and your pH to 7.7. There are many other variables such as substrate, bio load, that makes this not as simple as I would wish this to be for non-advanced aquarium keepers; but for those seeking simple adjustments for community aquariums or basic Discus, Betta, etc. fish keeping, this is still a reasonably stress free simple solution.
You may have to experiment some such as using 35% RO water, but once you find a percentage, unless your tap water chemistry changes (which is more common that you may think), your results should then be consistent.

Prior to introducing the RO (or DI) water to "Cut" your tap water, I recommend the addition of essential mineral ions such as by use these methods/products:
*Soaking a Wonder Shell in the RO water
*API Electro-Right
*Kent RO Right
*SeaChem Replenish
*Tropic Marine Pro Discus Mineral
The later two being the better products being the best in my experience.

For advanced aquarists that are confident in their use of buffers, mineral and electrolyte replacements may use a higher percentage or even 100% RO/DI (See: Use of RO or DI Water in Aquariums).

You can adjust this percentage up with subsequent water changes as you find your “sweet spot” in pH, but remember that pH stability is often much more important than the actual number. Also be careful in using bottled drinking water assuming it has proper minerals, it usually does not.

Calcium is also very important to Amazon basin fish as well as other fish too albeit in lesser quantities than say Mollies or Rift Lake Cichlids (despite some old school commentary to the contrary) and the lack of calcium minerals is not usually as evident in short term observations, however long term health and disease resistance will suffer (such as HITH disease) without a constant supply of trace amounts of calcium and other reducing mineral cations. I should also note (despite common misunderstanding about water chemistry) that the addition of these mineral ions does not directly effect pH only GH. Please refer to the section about Calcium earlier in this article as to why.
Calcium should also be included and many electrolyte replenishers (such as Electrolyte) do not add adequate amounts of Calcium (only trace electrolytes such as found in the before mentioned Electro-Right). Please note that I am not putting down these products, as I have used them and they are very good for replenishing this important electrolytes including some chlorides Wonder Shells may miss), they are just not complete as per continual replenishment of positive calcium canions (necessary for Redox health). Wonder Shells can also be used with these products to provide better balance in this area.

Closed Aquarium Environment; an aspect that GH & Calcium with Amazon River/ SE Asia Water is that is missed by many (as per my email and other conversations) is that while the Amazon River may be a very low GH, this is an open environment where mineral cations are constantly replenished from the Andes Mountains. Similar is for the monsoonal flows in SE Asia (although not as regular). However the aquarium is a closed environment and depletion of mineral cations can be very quick, especially when lower GH levels are maintained (see the earlier section about "Depletion of Positive Ions").
The bottom line is this closed environment aspect of an aquarium that is missed by so many, often sadly due to "cut and Paste" articles that permeate the internet or are repeated by some aquarium/fish stores.

For those who still do not understand biochemistry as it applies to fish and all animals and falsely believe this is the only article stating the importance of calcium and other positive mineral ions for Discus, Bettas, German Rams, or even Shrimp; maybe they should try reading some of the research into Redox Balance (& Mamoon Kundi pHd work in the area of Redox Reduction) or read others such as Atison Phumchoosri or Marc Weiss (both well known for their work with soft water fish)

Be patient with this process as you want slowly lower pH (and KH well), as earlier stated you can increase your percentage of RO or DI water each time you change water however you do not want stress fish by a large RO percentage right away.

Also keep in mind that Peat, Bio Lif, Driftwood, and Aquarium Drift Wood , Frog Moss (see picture to the left) will slowly work on pH and KH reduction, NOT overnight!
Driftwood can be cut into increasingly smaller pieces for more water exposure to pH reducing tannins to increase effectiveness.

These products act as low pH buffers and will generally not bring down a pH immediately (nor do you want to either!), if your KH is especially high this will take time and subsequent water changes with blended RO water (which will “cut” the pH). However you can boil peat in a pot or Bio Lif (almond Leaves) to release all the acid faster.
Pillow Moss/Frog moss is somewhat of an exception from my experiments as I have performed experiments with a 15 gallon aquarium utilizing two Frog Moss pieces; the Frog Moss reduced KH from 60 ppm to 10-20 ppm in one week.

In a related thought, if too many tannins are released, using less peat, peat, or driftwood may be advised (as noted earlier Driftwood can also be cut into pieces).

A true acid buffer such as SeaChem Acid Buffer can also be used for more immediate results, however it is a must to use such acid buffer products with either SeaChen Alkaline Buffer or even just baking soda so as to maintain a stable pH (and also provide CO2 for live plants if kept).
I personally recommend the use of Acid Buffers only during set up and water changes, and recommend the use of Driftwood, Indian almond leaves, peat, etc. for constant but slow acid buffers in the same way I recommend the use of Wonder Shells for a more constant supply of essential mineral ions (rather than products that provide a temporary supply of mineral ions such as Atison’s Spa).

As I noted earlier in the general pH section, is although Peat, Driftwood, Bio-Lif or similar Almond Leaf products will lower pH, it is done via the slow production of acids such as tannins and if your tap or well water used is very high in carbonates or bicarbonates (which are KH buffers) you will see NO effect on your pH and you will need to lower these KH buffers (not totally eliminate) for these to be effective or allow for time as the tannins slowly dissipate the carbonates via interaction with the acids/tannins. This is why I generally used blended RO/DI water (often with fast acid buffers) as noted earlier for my water changes for my clients in the LA area where high carbonate tap-water was a way of life.

Other products for softening water such as Atison’s Spa, Bio Lif, etc.

Other products that are popular for softening water, lowering pH, and for creating an Amazon or Breeding environment include black water tonics and Atison’s SPA. I personally do not care for the old black water remedies as I find them to mostly work like the proverbial “chicken soup” placebo effect when put to actual tests and in fact I have seen harmful anaerobic bacteria added from these remedies.
Bio Lif with a constant supply of calcium ions provided by a second product would be my first choice (based on the benefits of constant mineral ions/cations as pointed out earlier in the article), followed by still excellent Atison’s Spa or Marc Weiss Instant Amazon (which also contains calcium) as other choices, albeit with a less constant supply of mineral ions.

As to Atison’s SPA, this is growing in popularity among Betta enthusiasts due to mega internet site promotions by Dr. Fosters and PetsMart.
This is a good product as per the use of Almond leaves that it contains (and its additional Calcium which is often a forgotten mineral necessary for healthy breeding) and is vastly superior to Black Water or peat, however it uses almond leaves are very refined which causes the loss of potency of beneficial as compared to the superior Bio Lif.
The use of Bio Lif OR other peat sources (Pillow Moss, etc.) supplemented by a separate addition such as with Wonder Shells or a drip method of liquid calcium (a other minerals, both “soft” & “hard”) with products such as SeaChem Replenish in a volume of water with will add a constant supply of important mineral cations that are essential for fish or even water changes using high calcium water.
The Betta breeders in LA I know use Bio Lif and get better results over “Spa”, however these guys are not active in Betta or Discus groups/forums, so this does not get out.

Finally it is important as you also want to note that the Amazon River starts high in the Andes Mountains where it picks up a lot of minerals only to be buffer “down” by organics such as peat and bio-decay (as well as dilution from copious amounts of rain water). Bio decay will also add nitric acid which will further lower pH (providing you do not over clean the substrate). Because of this, do not try and lower GH (only carbonate hardness), calcium in particular as this is still an important element for osmoregulation in Discus and other Amazonian fish as well (calcium aids in a reducing Redox as well!).

Do NOT use pH lowering products such as pH Down (or pH Up) as these will just cause a roller coaster effect on your pH, in fact I have seen both from my use or a client adding pH Down (or similar products) the pH drop as desired only to rebound very quickly due to alkaline buffers often present in most tap water sources (depending upon your location of coarse). This rebound can quickly shock and stress delicate fish since as noted earlier a change in pH up or down of just one point is a ten fold change.
Better to concentrate on a stable KH and use blended or re-mineralized RO water along with pH buffering products such as Bio Lif (almond leaves), peat and Drift Wood (Mango Wood), or at the very least use true acid buffering products such as SeaChem’s Acid Buffer (which should be always used in combination with an alkaline buffer, even baking soda.

FACTS ABOUT MINERALS/ELECTROLYTES AND CALCIUM;

• All fish require calcium and other mineral cations, including discus, bettas, tetras and other soft water fish. In fact the lack of electrolytes and calcium is a MAJOR problem for poor health in bettas and discus. Good water management should ALWAYS insure good electrolyte levels along with water changes and other aquatic husbandry practices. Use of water conditioners as well mineral blocks can help insure this.

• Calcium and other minerals added to fish food made from poor quality ingredients are usually not adequate for proper health (some studies show these added minerals block absorption). Calcium and other minerals in the water (especially for marine organisms) as well as foods high in natural minerals such as Spirulina are also important.

• Although the addition of calcium and electrolytes may initially stress fish that have had low electrolyte levels, this does NOT prove these elements detrimental any more than changing water in an aquarium that is long over due for a water change (this too may initially stress fish). A GH of 20 dGH (over 350 ppm) is easily tolerated by ALL fish especially when calcium makes up the majority of this GH. Separate calcium and magnesium tests can verify this.

• Although RO or DI water may be very clean and pure, by itself it can be VERY detrimental to fish without the addition of electrolytes and essential minerals such as calcium. If you use it, make sure you reconstitute it. I generally use Reverse Osmosis (RO) water blended with tap water (for soft/low pH fish such as discus), then adding a Wonder Shells, Replenish or similar for added trace elements as well as alkaline and acid buffers).
It is even more important to reconstitute 100% RO or DI. Please see the Chart in the KH Buffers Section for further information about the use of Alkaline and Acid Buffers together and at the correct ratios.

"Drinking Water" sold in stores is usually just RO water with SOME minerals added for “taste” and is FAR from appropriate for aquarium use. Usually true spring water is OK. However RO or DI water is fine for marine use (in fact I recommend it) as salt mixes add all the trace elements needed.

• It is possible to have adequate calcium and electrolytes without raising pH to a harmful level for discus, bettas and other fish that generally prefer low pH water (many discus breeders in LA keep there discus pH higher than in the wild anyway).

Quick Tips For Adding Buffers, etc.:
Daily Dosing	For those who prefer perfect KH and interaction of Acid & Alkaline Buffers, this might be for you. Adding Acid and Alkaline every morning can provide the chemical reaction to add additional CO2 for plant enthusiasts. However you still need to experiment to find the sweet spot in your aquarium chemistry that does not result in too high or low KH by the next morning and adjust ratios accordingly.
Weekly or Bi-Weekly Dosing	This is the most common and is the method I chose with the vast majority of my clients. Simply figure the amount of Alkaline Buffer needed to maintain the desired KH for this time period. For example if 150 ppm is desired adding buffers to 170 ppm and then finding your KH at 130 two weeks later is generally acceptable as long as adding buffers at this time does not cause a pH rise of more than .5 Except for Amazon River or similar aquariums, generally Acid Buffers are not called for in this method
Fast pH/KH Drops between dosing	Look for too much decomposing mulm, peat, driftwood, pillow moss, over feeding, overly saturated canister filters, etc. Or simply too much Acid Buffer (if used)
Fast pH/KH Rises between dosing	As noted more in depth in this article, this can simply gassing out of new water, so allow at least an hour before a pH test after adding. Use of decorations that might have carbonates contained there in, such as Coral Skeletons in freshwater. Use of 10%, 25%, or even higher amounts of RO water may be a solution rather than chasing the exact blend of Acid & Alkaline Buffers. Also over use of alkaline buffers can have this result too.
Test, Test, & Test	While I wish it were possible to give an exact measurement for everyone, I cannot. The FACT is aquarium keeping is a science and EVERY tank is unique for a multitude of reasons and hopefully with a reading (or maybe 2 or 3 readings) of this article you will understand how best to keep your aquarium.

FRESHWATER TANK SET UP SUGGESTIONS FOR WATER CHEMISTRY

I should note immediately that these suggestions are NOT meant to be the only way, these are simply suggestions based on experience and good science/research.
What is most important is not the how, but the FACT that many mineral cations are essential for fish health from Freshwater Discus to Marine Reefs.
Often experienced aquarists do not take extra steps to provide these (a mistake often made when utilizing the "Walstad Method" of aquarium keeping), yet they inadvertently provide essential positive mineral ions and carbonates via good aquatic husbandry, substrate choices and more.
However it is not correct to state that just because one does not take extra measures, others should not as well. Also, it is noteworthy that even experienced aquarists may not be maintaining the best environment possible, as statements such as: “I do not maintain or check my positive mineral ions and my fish are fine” prove absolutely nothing, as many fish adapt to poor environments but do not thrive as well as they could and good science states otherwise to such statements.

Also as noted earlier in this article (the KH section); there are NO EXACT ratios as each aquarium is very unique; so testing is 100% required and even then testing should be performed hours or even a day later after addition of mineral and/or buffering products to allow the chemistry to "settle". With peat, pillow moss, Indian Almond leaves (Bio Lif), driftwood and similar; this "settling in" may take weeks.

Once you establish a "sweet spot" for your unique aquarium environment, use the blends ratio numbers that work for you! This may mean a drip system, mineral blocks, daily small doses of buffers (so as to have constant reaction and very little change in KH), or weekly or even bi-weekly additions of buffers as I usually did with my aquarium maintenance clients (as I could not be at my clients every day, so the buffers and mineral replenishments had to be adequate for the gap between visits).

Basic Widely Mixed Community, including Tetras, Gouramis, Catfish, Loaches, Danios, Livebearers, many Cichlids, etc;

*Aim for a pH that is stable (not an exact number) in the range of 6.6 to 7.8.

*A KH of anywhere from 80 to 150 is generally good and this can be maintained with products such as Sea Chem Alkaline Buffer.
If tap water is high pH/KH I would recommend using 10-20% Reverse Osmosis Water and/or products such as Frog Moss or Mango/Drift Wood to counter the high pH/KH.
If your water source KH is low (tap water, etc.), adding buffers to your tap or other water source to bring it up to the desired KH should be performed with every water change.

Small amounts of KH buffers will likely need to be added in intervals in between water changes based on KH tests.

*GH is best between 150- 300, although this can be misleading in that CaCO3+ (& other positive mineral ions) can be depleted and your GH still reads high. The use of Wonder Shells or the slow drip addition of powdered or liquid mineral supplements such as SeaChem Replenish can help with this (simply adding these liquid or dry mineral supplements on a regular basis can work well too).
1-5% water changes daily can help as well provided your water source has these important mineral cations.
If salt is necessary with lower pH mixed aquariums, I generally just use water softener salt or any plain salt.

Soft Water Low pH, KH Amazon River, SE Asia or West African Aquarium

*As with the previous section (Basic mixed aquarium), aim for a pH that is stable, do Not chase pH. Chasing pH is all to often performed by inexperienced Discus, Angelfish, etc. keepers. In fact I know of two very successful commercial Discus breeders that maintained their Discus pH at about 7.0-7.4. The bottom line is the risks of poor Nitrogen Cycling and more of attempting to keep a 6.0 pH are simply not worth any perceived benefits of a pH of 6.0
From the above cited article:
"It is also noteworthy that the primary nitrifying bacteria are affected by pH. PH levels of 7.5 to 8.5 are considered optimal for healthy nitrification of ammonia, and nitrites, as nitrification rates are rapidly depressed as the pH is reduced below 7.0. At 6.0 basically all nitrification ceases!"

*KH is still important with these soft water fish (maybe not as important as with a Rift Lake Cichlid). The reason is to prevent pH spikes (usually down from other methods used for a soft water environment such as peat or even simply from biological waste breakdown). Generally utilize KH buffers (such as SeaChem Alkaline Buffer or even Baking Soda) to maintain a KH of about 50-80 ppm if necessary.
The use of natural acid buffers such as Frog Moss, Peat, Indian Almond Leaves, and/or Driftwood should also be employed to balance the pH and react with the carbonates provided by the KH, which in turn provides CO2 for live plants that are often kept in this type of aquarium.
Generally Almond Leaves, Driftwood, and many forms of Peat are "Slow" acid buffers, while Frog Moss tends to be a more fast natural acid buffer.
The use of a chemical "fast" acid buffer such SeaChem Acid Buffer should be considered at set up and for water changes (or in between if there are issues with pH climbing or if more CO2 is needed (a KH buffer must be used to cause the reaction that produces CO2).

*GH; the main importance with soft water fish is not GH per say, rather the very important positive mineral ions (such as Calcium+++ or Magnesium+++) that have been proven to improve fish health and prevent diseases (such as Columnaris). Since GH test kits give only half the “picture” (a Redox Meter or even a simple Methylene Blue Redox test can help), a target GH does not necessarily mean there are adequate mineral cations.
However a GH of 100-150 that is regularly replenished should aid in providing these mineral ions.
For these soft water aquariums the use Reverse Osmosis water (or partial RO water), then the use of a more measured dosing mineral/electrolyte product such as SeaChem Replenish to add these important minerals without making the aquarium GH climb more than desired (although as noted earlier, a GH over 150 is not the problem many soft water fish keepers make it out to be), then the possible addition products such as Wonder Shells or similar products (such as utilizing a drip of or AragaMix) at 1/4 dose or 1/4 block can aid in providing constant supply of important mineral cations.

Please see the section earlier in this article for much more about Amazon River/SE Asia/West African Water Chemistry/pH, GH, KH

Goldfish/Koi

*Aim for a pH that is stable, as before, not an exact number but in a range of 7.2 to 8.0 should be fine.

*A KH of anywhere from 100 to 200 is generally good and this can be maintained with products such as Sea Chem Alkaline or Marine Buffer. With Goldfish, the use of a “complete” buffer such as the SeaChem Marine or Malawi may be useful for a more balanced GH/KH, however in hard water areas the regular alkaline buffer all that is needed for goldfish. If your water source KH is low (tap water, etc.), adding buffers to your tap or other water source to bring it up to the desired KH should be performed with every water change.
Small amounts of KH buffers will likely need to be added in intervals in between water changes based on KH tests.

*GH is best between 200- 300, although again this can be misleading in that CaCO3+ (& other mineral cations) can be depleted and your GH still reads high.
The use of Wonder Shells can create a constant supply of necessary positive mineral ions or the use of either a drip/dosing or simply scheduled use of liquid or dry mineral supplements (such as Replenish should be employed to supply these essential mineral ions.

Livebearers

*Aim for a pH that is stable, as before, not an exact number but in a range of 7.2 to 8.4 should be fine.

*A KH of anywhere from 150 to 250 is generally good and this can be maintained with products such as Sea Chem Buffer. The difference from the mixed community tank is that I recommend using more advanced buffer that includes minerals such as Marine or Malawi Buffer, although you obviously want to test your KH to find the “sweet spot” in the amount needed to fit your bio load and tap water adjustments.
Generally Acid Buffers are not necessary for livebearers as the normal bio processes produce more than enough acids that react with alkaline buffers and supplementing with acid buffering products would require even more Alkaline Buffers for higher pH/GH preferring fish.
If your water source KH is low (tap water, etc.), adding buffers to your tap or other water source to bring it up to the desired KH should be performed with every water change.
Small amounts of KH buffers will likely need to be added in intervals in between water changes based on KH tests.

*GH is best between 250- 350, although again this can be misleading in that CaCO3+ (& other mineral cations) can be depleted and your GH still reads high.
The use of Wonder Shells can create a constant supply of necessary positive mineral ions and the use of crushed coral gravel can supplement this further if desired.
SeaChem Cichlid Salt is also suggested to provide a balance of sodium chloride salt and other essential minerals and can be used with or without our mineral supplements (such as the before mentioned Wonder Shells); testing your KH & GH before and after water changes as well as intermittently will help determine the amount to use.

Rift Lake Cichlids

Similar to livebearers, except many aspects should be often higher yet in alkalinity/pH, especially for Lake Tanganyika Cichlids.

*Again, aim for a pH that is stable, as before, not an exact number but in a range of 7.8 to 8.4 should be fine for most Malawi or Victoria Cichlids and 8.0 and higher for Lake Tanganyika Cichlids.

*A similar approach to livebearers except the goal is for a slightly higher KH (more so with Tanganyika Cichlids) with a KH of anywhere from 150 to 300 being generally good and this can be maintained with products such as Sea Chem Buffer.
If your water source KH is low (tap water, etc.), adding buffers to your tap or other water source to bring it up to the desired KH should be performed with every water change.
Small amounts of KH buffers will likely need to be added in intervals in between water changes based on KH tests.

*GH is best between 250- 350 (or even higher) and as stated before, do NOT depend on your GH test kit to give you the full picture of the yet even more important for Rift Lake Cichlids mineral cations. These large lakes have a large in flow and reserve of these ESSENTIAL positive mineral ions that CANNOT be easily duplicated in an aquarium, eve with the use of crushed coral gravel (although this is certainly a good start). The use of an even more fine oolite coral sand is eve better for supplying these mineral cations important for osmoregulation, Redox Balance and in the end good fish health.
The use of Wonder Shells can help with a more steady supply of these mineral positive electrolytes. Regular water changes, especially with high mineral water (often tap water is great for this) should NEVER be over looked as well. The use of Sea Chem Saltcan provide both sodium chloride salt and additional minerals and can be used with Wonder Shell, Replenish or similar mineral supplements or by itself.

List of Products for Aquarium Chemistry by Category
(Please note that this is not intended as a complete list of products, however similar products can be found by drawing conclusions from this list;

Alkaline Buffers:
*SeaChem Marine & Malawi Buffer
*SeaChem Alkaline Buffer
*SeaChem Cichlid Salt
*Baking Soda

Acid Buffers:
*SeaChem Acid Buffer
*Frog Moss (Pillow Moss)
*Bio Lif (Indian Almond Leaves)
* Atison’s Spa (Indian Almond Leaves)
*Peat
*Driftwood

Mineral Replenishment:
*Wonder Shells
*SeaChem Replenish
*Aragamight
*SeaChem Cichlid Salt (this also adds Sodium Chloride Salt)
*Oolite coral sand
*Crushed Coral (a very poor source)

SUMMARY:

There is much scientific practical evidence to support the need of Calcium, a healthy KH, GH, and Electrolytes in a Freshwater Aquarium. This is more widely known for marine aquariums, however these important parameters and the interaction they have on fish health in freshwater are often missed. The minerals often found in GH (Calcium in particular) have also shown to be effective for BOTH prevention and treatment of Hole in the Head (HITH) in many cichlids.

Many freshwater aquarists will often concern themselves with a certain pH all the while missing the importance KH plays in the stability of pH even in Amazon River tanks (where low pH buffers should also be employed).

The need for calcium by all creatures is well documented, especially in studies outside the aquatics industry/hobby. Calcium and other elements found in a healthy GH are important for osmoregulation in ALL freshwater fish and even plants (saltwater organisms too).
These elements also aid in a healthy Redox Balance as well. The addition of pH up or pH down products is often counter productive vs. using products that stabilize your aquariums KH and GH, these products often result in a bouncing pH.

Products such as Wonder Shells will help with your calcium, magnesium, GH of your aquarium (especially important CaCO3+ which are quickly depleted, even when GH tests kits show abundant Calcium/minerals the beneficial positive ions may be depleted).
I prefer these (or SeaChem Replenish, Aragamix) over crushed coral for adding calcium, magnesium and electrolytes as from my experience. Wonder Shells also are available in a medicated version for control of aquarium ich and fungus.

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