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Aquarium and Pond Calcium, electrolytes, pH, GH, KH, Magnesium

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AQUARIUM CALCIUM, KH, Ph, GH, MINERAL CATIONS/ELECTROLYTES;
Aquarium Chemistry; The Importance of maintaining healthy positive calcium ion levels, GH, pH, KH and electrolyte levels (freshwater & Marine)

•Overview •KH (including the use of Crushed Coral)
•GH (& magnesium) •Calcium
•Electrolytes • Use of RO/DI Water, •pH , • Correcting unstable KH/pH
•Amazon River Tanks, •Facts about Calcium and Electrolytes
• Freshwater Aquarium GH, KH, pH chemistry suggestions (Community, Livebearer, Rift Lake Cichlid) •Summary


Calcium Electrolytes, KH, GH, pH for fish, saltwater, freshwaterAQUARIUM CHEMISTRY OVERVIEW;

By Carl Strohmeyer
Updated 8/07/10

Many aquarists overlook the need for electrolytes; mineral cations such as calcium & magnesium and the effect of KH (Carbonate hardness) in their freshwater aquarium.
Minerals such calcium are essential for osmotic function in fish and many aquarists make the mistake of believing that some fish such as Discus do not require Calcium or minerals when in reality (based on many studies in biochemistry) these mineral cations are essential and GH test kits to not give the full picture (Important, please see the GH section for more).
Fish will often adjust to poor electrolyte and calcium (& other necessary Redox reducing elements), however this does not prove this is best for the health of your fish anymore than how fish will often adjust to aquariums that are crowded with infrequent water changes (which is also not good for long term fish health).
Aquariums that are overdue for a water change, with high bio load, lack mineral/electrolyte replenishment, or simply initially start out with incorrect chemistry often results in inadequate mineral and carbonate chemistry necessary for bio function. Correction of this problem via water changes and/or addition of mineral or carbonate supplements may even show initial stress until the inhabitants adjust to the improved water quality.

Often aquarists in both fresh and saltwater worry too much about pH while ignoring the importance of GH (for important mineral cations/electrolytes) and KH (alkalinity in SW) as to pH stability which is more important than the actual pH number in freshwater. In marine aquariums the actual pH number is of higher importance than in most FW aquariums (due to the fact here are much lower natural fluctuations in pH in natural bodies of saltwater), however even in saltwater a correct alkalinity (KH) is a must for proper buffering of marine pH and as well elements such as Calcium, Magnesium and Chloride are also very important to a healthy saltwater aquarium as you will read further in this article.

Popular aquarium traditions state that only certain fish need water high in electrolytes and calcium, this is only partly true. The Fish Body (organism) is alkaline by nature and is constantly attacked by free radicals which are usually acidic. While freshwater fish absorb needed H2O (saltwater drink constantly), the need for these electrolytes and calcium for some fish (such as Amazon River fish) is lower than some, however Proper Osmotic function stills requires that calcium and other electrolytes be present in the aquatic environment as well as foods. This is why I have found that even fish such as Ram Cichlids thrive in a Reducing environment that has a Calcium level that often brings the GH over 150 ppm (so as to provide positive mineral ions that are rapidly depleted even while the GH may still read over 150 ppm) and why the aquarium traditions of lower GH for certain fish are only half correct as they miss the aspect of balancing water with important mineral cations as well as with acid buffers.

KH is basically the alkaline buffering capacity of your aquarium (there also is an opposite acid buffering process which when combined with KH is important for planted aquariums or low pH aquariums; see pH/Amazon River Section), a KH above 50 ppm helps prevent sudden drops in pH. KH (carbonate hardness) is an important source of energy for nitrifying bacteria that eliminate ammonia and nitrite. In addition, carbonates are used by plants for photosynthesis when carbon dioxide (CO2) is absent.
KH (Carbonate) buffering is especially important with Livebearers, Goldfish, East African Cichlids (Rift Lake), Brackish and many other freshwater fish (which should have an even higher KH over 100-150 or more).
In saltwater aquariums your KH (which is generally referred to as alkalinity) should be an absolute minimum of 240 ppm.
The production of Nitrates (via processes that are similar to the production of nitric & carbonic acids) will slowly reduce your ph, but an adequate KH will keep a more stable ph. This is important to note, if your KH is low and your ph has been dropping, a large water change can cause stress on your fish, or even kill them (don't get me wrong, water changes are VERY important, just be careful with large water changes to correct very poor conditions). What is missed by many aquarists is that the pH scale is logarithmic, which means a 1 point drop/rise in pH is a tenfold change in acid or alkalinity (for more about this please read the pH section).

A proper electrolyte and calcium level, GH, & KH (by the term “proper” I mean what is the best level for the fish kept) can also have a positive effect on the aquarium Redox Balance, which recent studies have shown to be more important to fish and other animal health than pH. A positive mineral ion balance contributes to the Redox reduction potential of water, maintaining a more stable water environment, better clarity and the excess electrons attach themselves to free radicals, improving disease resistance. For more information here, please see this article: “The Redox Potential/Balance in Aquariums and How it Relates to Aquatic Health”

Map of Water Hardness, United States For those who use test kits that provide results in dKH or dGH, you can convert dH (German hardness) to ppm by multiplying your dH by 17.9

To the left is a map of average water hardness (combined general and carbonate hardness) in the USA. Please click on the picture to enlarge).

Please read the full article below and referenced resources for a much more in depth explanation of the often misunderstood aspect of aquarium chemistry:

     
 

KH (CARBONATE HARDNESS/PH BUFFERING):

An important consideration of KH is that you can generally safely add the buffers (both freshwater and saltwater) that effect KH without sudden changes in chemistry (unless your freshwater KH is under 50 ppm already), unlike a direct ph or GH change. Maintaining these KH 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).
The chemistry behind KH is quite complex, so I will not go into too much detail, however in the most simple terms I can think of; is 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 (which is why a KH of 50 ppm is all you would want with your discus, while a KH of 200 plus is recommended for African Cichlids or Marine Fish). 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) is caused by metals combined with a form of alkalinity. KH (or Alkalinity, which is the more technically correct term) is the capacity of water to neutralize acids and is caused by compounds such as carbonate, bicarbonate, hydroxide, and sometimes borate & silicate. In contrast, non-carbonate hardness (GH) forms when metals combine with anything other than alkalinity, which why (despite many incorrect claims to the contrary) calcium does not raise pH directly.
Carbonate hardness is sometimes called temporary hardness because it can be removed by boiling water. GH (noncarbonate 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 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, 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. Aragonite and Seachem Cichlid Salts can also supply some carbonates as well.

Soft water 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 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). However I recommend countering the KH Buffer with Acid Buffers such as Bio Lif, Atison’s Spa, Driftwood, SeaChem Acid Buffer, etc. as a healthy lower pH has a “balanced equation” of both acid & alkaline buffers.
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 not maintain as stable of a KH.
I should also note that I do find the use of Neutral pH regulators as helpful for community aquariums as a more natural balance of carbonate buffers and acid buffers (both natural or supplemented) for keeping a healthy aquarium chemistry equilibrium.

Added calcium and other elements keep a more balanced KH/GH and add necessary trace and minor elements (see GH and Calcium sections of this article for more in depth explanations).
This article will explain a little more about the need for other elements besides Baking Soda (NaHCO3): "Proper Osmotic Function; Electrolytes".
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) 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 (as I note this product many times 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!

Further explanation of common Buffers used to raise KH (& 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 unlike Baking Soda. 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).
*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 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 as baking soda would if large amounts are used, however it still is more stable and moves pH much less dramatically than baking soda making it still a much better choice in FW.

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 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 high bio loads and without adequate water changes (even skimming can remove some elements). What Crushed Coral are better for is necessary minerals and in the case of Aragonite, it generally has a few more minerals in higher concentrations such as the important mineral (for corals), Strontium.
HOWEVER 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), which is why use of these “gravels” (technically these are coral skeletons) should be used 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, although again I will point out not a lot 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 do to the FACT of its mineral make up (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 due to the fact it 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 tests (especially in marine aquaria) show that its use to increase KH (& Calcium and other minerals) simply is poor, and statements to this point are simply false based on very simple research that anyone can perform!


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 buffers such as Sea Chem Alkaline Buffer are still important, however I like to counter these with natural lower (acid) pH “buffers” such as Indian Almond Leaves , Peat, 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, Almond Leaves, etc.), you can use immediate acid buffers with KH (carbonate) buffers for quicker results, such as SeaChem’s Acid Buffer.

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 see the section about too low pH and KH problems lower in this article for more about solutions/causes to an unstable KH (near the bottom of the pH section).

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

GH and KH Test Kit
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 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 proven false myths. In reality freshwater generally it 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 a call, email, etc. over the years what do about their so-called high GH, often this GH turns out to be around 200 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, 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 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.
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
CaribSea AragaMightWonder ShellProducts 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.
Finally the obvious way to replace minerals (electrolytes/cations) is via regular water changes, 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 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 , help 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 magnified
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 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 which should be 1200- 1400 ppm) 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/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.
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 for calcium (also Lime):

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 and pH, however it is simply CaO and does not contains other elements necessary including bi-carbonates and magnesium to name but a few.

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 OR SEALAB


ELECTROLYTES;

Aquarium electrolytesThis section is somewhat redundant, as the before mentions Calcium and Magnesium as well as 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.
Salt is commonly used in a dose of one tablespoon per 5 gallons (20 liters) in freshwater aquariums. This is one way to add some electrolytes (Sodium Chloride), but this should not be the only.
Wonder Shells add many other electrolytes (especially the essential Redox Reducing “Hard” electrolytes, which is a reason I strongly recommend these, especially in smaller tanks). Products such as SeaChem Replenish also adds some essential Electrolytes, more so in the “soft” electrolytes and in more trace amounts (products such as the slow dissolving Wonder Shells add these electrolytes over more longer sustained periods and even though more “hard” are still quite useful 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 also will 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 poor treatment for a full blown infection despite many anecdotal comments by many.

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 Scale Diagram
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 for 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 Aquarium cleaning Machine 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, some driftwood, Mango/Drift Wood , and dried almond leaves (Bio Lif ) will aid in lower stabilization (for really troublesome high pH aquariums, cutting pH/KH with blended RO water may be necessary, see below).
Please note that Peat, Driftwood, etc. mostly lower pH via a slow release of acids such as Tannins, and that 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 Bio Lif or Peat (I recommend Bio Lif), I suggest at least temporarily suspending the use of carbon, you can still use it, just not after initial use of Bio Lif or peat as Carbon removes many of the elements that these products add that make them work (much like how carbon can remove other essential trace elements and non-essential trace elements and toxins (carbon cannot tell the difference between good and bad). 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). I have seen Discus (a fish which comes from waters often under 6.5) breed in aquariums with a pH above 7.5. What is stressful is a pH that is not stable therefore a good KH 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 ppm and a Redox Potential around -300 mV than with a pH under 6.5 (please note that these numbers just given are for discus, for many fish such as livebearers I kept a much higher KH and GH).

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, if there are carbonates (KH) in the water (even more common in well water from my experience), the pH will rise (sometimes appreciably).
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/or Mango Wood. 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.

Corrections for unstable KH/pH
(or too low pH or KH problems):


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 and/or KH you will have problems maintaining 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 some crushed coral/aragonite to a nylon bag and place this in the filter AND/OR you can add can add some Buffer to the water (I do not recommend Baking Soda as noted and explained earlier in the article). 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 crushed coral/aragonite (the Marine is safe for FW use and I actually prefer it over the Rift Lakes Buffer). Wonder shells will help with Calcium and GH and will help maintain KH, however they are NOT as useful for water that is already very low in KH/pH and needs to be brought up. 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.

If the tap/well water is fine, I would look at tank conditions and change more water, more frequently. Here are a few possible problems to look into:

*Too high of DOC (dissolved organic compounds) caused by organic debris/mulm, this can be spotted by a KH of (for example) 50 ppm after cleaning, addition of buffer, and correct out of the tap, however if KH drops rapidly after the initial measurements. 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.
*Mulm buildup under rocks/décor and in canister filters/ Wet-Dry filters. Canister filters in particular if let go more than 6 weeks can buildup a lot of decomposing mulm that will add acids to your water.
*Too much Driftwood/Mango Wood. Some driftwood in particular can be full of tannins that will lower pH/KH.
*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.
*In frequent or poorly conducted water changes/cleanings. Please see this article for more: “Aquarium Cleaning; Methods and Reasons”
*Even an otherwise normally good #3 grade of gravel that is regularly vacuumed may still harbor organic mulm, this is particularly rue 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.

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


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

For Amazon/SE Asia River/West Africa Water (lowering pH)
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 which is much more important than the actual pH.

RO (Reverse Osmosis) or DI (De-ionized) water is used to aid in pH (& KH) reduction.
I would recommend only using no more than 25% to start with the remaining 75% well or tap water (although for advanced aquarists that are confident in their use of mineral and electrolyte replacements may use much more RO/DI); then and adding a Wonder Shell for about a day to this water to add back essential minerals (and/or other forms of trace elements such as API Electro-Right, SeaChem Replenish or Tropic Marine Pro Discus Mineral, with the later two being the better products IMO over Electro-Right).
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.

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, maybe they should try reading some of the research into Redox Balance (& Mamoon Kundi pHd work in the area of Redox Reduction) or read how others such as Atison Phumchoosri or Marc Weiss (both well known for their work with soft water fish)

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.

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 , and Mango Wood/Driftwood will slowly work on pH and KH reduction, NOT overnight! These products act as low pH buffers and will 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.
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 slightly superior Bio Lif. The use of Bio Lif 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 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 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 trace elements such as calcium. If you use it, make sure you reconstitute it. I generally only use Reverse Osmosis (RO) water blended with tap water (and then generally in low pH fish such as discus, adding a Wonder Shells, Replenish or similar for added trace elements). Drinking Water 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).


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, 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 (via a not always reliable GH test) 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.

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 Bio Lif or Mango/Drift Wood to counter the high pH/KH.
*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, Angle, etc. keepers.
*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 slow acid buffers such as Peat, Indian Almond Leaves, some 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.
The use of a 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. Wonder Shells or similar products (such as utilizing a drip of SeaChem Replenish or AragaMix) at half dose or half mineral block usually addresses this important water parameter.

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

Golfish/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
*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.
*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
*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
*Baking Soda

Acid Buffers:
*SeaChem Acid Buffer
*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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