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Although not a well known process among many aquarists (with much misunderstanding of both sides of the equation by even some advanced aquarium keepers); the implications of Redox for a healthy aquarium are quite far reaching, and thus important for any aquarist considering moving from basic aquarium (or pond) keeping to advanced to understand.
As well, even the average aquarist should consider this water parameter when all other parameters check out, yet fish continue to be susceptible to disease this may be an important parameter to consider as growing research in human disease resistance, and even plant growth also shows.
However some in the aquarium keeping community still seem to be in the dark as per this growing documented research.
Redox, also known as Redox Potential, oxidation potential, & ORP (oxidation reduction potential) describes the ability for the loss of an electron by a molecule, atom or ion to the gain of an electron by another molecule, atom or ion.
Without this ability to gain electrons, many minerals cannot be absorbed and properly assimilated. So it is very important to keep a healthy Redox Balance via proper dissolved oxygen levels, proper positively charged mineral levels (such as Calcium and Magnesium), and even level 1 or higher UV Sterilization.
(Please click on the picture above/right to enlarge for a better view)
Many in the past have stated exact numbers are the "best" Redox reading for an aquarium. My research has found this to be incorrect.
In some aquariums, a higher Redox of 350 mV may be a good Redox to obtain (for oxidation) when high organics and decomposition is lowering water quality.
HOWEVER for a new or established aquarium that is properly functioning this is not a number you should be necessarily "shooting" for correct Redox balance, so please read on!.
*Oxidation describes the loss of an electron by a molecule, atom or ion.
Another way to look at this is to lose, or cause to lose, hydrogen atoms.
EXAMPLE: Redox processes such as the oxidation of carbon to yield carbon dioxide.
Oxidation is the LACK of electrons by a molecule.
Oxidation is when the molecule can accept electrons from a reduced molecule, thus oxidizing.
*Reduction describes the gain of an electron by a molecule, atom or ion.
Another way to look at this is remove oxygen atoms or add hydrogen atoms.
EXAMPLE: The reduction of carbon by hydrogen to yield methane (CH4).
Reduction is the GAIN of electrons by a molecule.
Reduction is when a molecule can give positive electrons to an oxidized molecule, thus ceasing the oxidation of the molecule.
Another example: Calcium (Ca2+) or Magnesium (Mg2+) which initially are composed of two positively charged ions immersed in a sea of movable electrons may have given up all possible electrons to cells/molecules under oxidation.
It is for this reason, then that positively charged calcium and magnesium supplies must be constantly renewed; without this “fresh” positively charged calcium, etc. your Redox balance will suffer.
Think of it this way; a battery "works" only when a positive and a negative electrode are present to maintain an electrical current. When the positive plates become exhausted, the battery is no longer functional, even though the metal plates and other "ingredients" for the battery are still present.
So it is that your GH or Calcium Test may show adequate minerals, but these minerals have been oxidized and thus rendering the test inaccurate as per ESSENTIAL positively charged calcium ions.
The above are over simplifications of the process, so please read on as I will go into further depth as the article progresses, especially as Redox relates to aquatic health.
Oxidized water with its Redox potential of +700 to +800 mV* is an oxidizing agent that can withdraw electrons from bacteria and kill it. The oxidized water can be used to clean hands, sterilize utensils, and treat minor wounds. *mV = Millivolts or 1/1000 of a volt of water conductivity
Reduced Ionized with a Redox Potential of -250 to -350 mV readily donates its electrons to unusual oxygen radicals and blocks the interaction of the active oxygen with normal molecules.
Substances which have the ability to counteract active oxygen by supplying electrons are called scavengers. Reduced water, therefore, can be called scavenging water.
Reduced water inhibits excessive fermentation by reducing indirectly metabolites. Please note that the oxidizers have a plus and the reducers have a negative in the chart to the left.
Click graph to enlarge
Here are a few reducers, in other words, elements or processes that can transfer electrons to another substance;
Magnesium, Calcium, Sodium, and the process of Photosynthesis involves both oxidation and reducing.
As one can see from the graph, elements such as most metals, as well as essential elements for aquatic life: Calcium and Magnesium are major reducers.
However because of this they are also most easily depleted (the elements at the top and the bottom of the graph are most easily depleted in their oxidation or reducing properties).
True UVC Sterilization also reduces, by electrically charging (adding an electron) and breaking down oxidizers in the water column.
Simple Test to Understand Redox: Take an 8 oz. glass of water, then add enough Potassium Permanganate to change the color to a mild red, then take any aquarium water conditioner such as Prime or Start Right and slowly add drops to the water and watch the red be "reduced" (neutralized) to a clear brown color.
What you are observing is the reduction of an oxidizer (potassium Permanganate) by a Reducer (generally Sodium Thiosulfate is used in these conditioners).
An important note, is that although oxidation is a necessary part of biochemistry for fish and all animals (such as for energy production), the NORMAL HEALTHY state is one of reduction.
During normal biochemical processes molecules that are normally reducers give up their electrons (in much the same way a car battery does until re-charged), so without a recharging via the addition of new minerals that are high in these electrons or even processes such as UVC sterilization (or even high PAR lighting), your aquatic biochemistry will suffer and eventually so will your fish!
One more basic generalization to consider before moving into more depth is this: Water that is of low pH (acid), in general, measures high ORP while water of high pH (alkaline) measures low ORP (please note that this is a broad generalization).
However, in natural water (generally spring water), acidity of minus ions and alkalinity of plus ions can coexist (more about this in Natural Redox).
See this website for more; Understanding pH and ORP
As a final note, 2012 human research has shown that an intake of 75% alkaline foods versus 25% acid foods are best for essential Redox Balance. This can be reasonably extrapolated to fish in the the water environment and foods should allow for this as well since the physiology of fish and humans are similar.
This of course often confounds those who constantly dump copious amounts of acid buffers or similar in their aquarium or worry about a generally fictitious "too high GH".
This picture/graphic below explains some basics of Redox:
It is important to note that Aquarium Redox can be a complex subject with some basic principles to also understand, however reading one section of this article will yield incomplete information. For this reason I recommend reading the whole article (as well as links provided) for a more thorough understanding. It may take more than one reading as well.
My research and interest in Redox goes back to my curiosity as to why certain aquarium maintenance methods were more effective in keeping healthy fish, and the common knowledge of the day did not fully explain results I was achieving.
I base this article on Redox studies as it corresponds to humans and all fish, animals, and even plants.
I have found from practical experience and research that a lot more can be learned from medical studies or other university level studies than from many aquarium articles and sadly some otherwise excellent forums (these articles/forums usually just take bits from another article without any real research, often with old ideas being simply regurgitated).
Originally my statement on Redox was: "I do not believe this is a subject that many aquarists should stress over", but a lot has been learned about this subject since I first started researching this in the 1980s.
The more I have studied this subject as well as the newest research shows that all aquarists should have at least a basic understanding of this subject as it has major implications for fish and aquatic health that often go against commonly held aquarium keeping beliefs.
I have also changed my opinions about this subject based on newer evidence about a balanced Redox.
One such opinion was "should you have a positive or reducing Redox". I based my earlier opinion on a higher Redox of +300 mV based on many studies of ocean waters and simply repeating what I was told, but newer human research and my own tests over the last 15 plus years have lead me to where I am now, that a BALANCED Redox is important.
What is a balanced Redox? The best research indicates a Redox that can respond to both the oxidation and reduction needs of the environment and more importantly the fish or other aquarium inhabitant. This can be a reading between +300 to -200 mV (a higher Redox is sometimes needed when oxidation is necessary due to high organic de-composition)
See the chart below (ecologically safe water): http://www.water-prox.com/mineral_redox_right.htm
Maintaining a proper Redox Balance (or Potential) which includes the reducing side of the equation is a lot like having an anti-oxidant vitamin in the aquarium water (although a more accurate description would be magnetically charged water).
The Aquarium Redox is also just one more parameter towards good disease prevention and long term fish health and growth.
Please see this article about Aquarium Disease prevention; “Aquarium Disease Prevention” .
Looking at the oxidizing side of the Redox equation; Bleach and Potassium Permanganate are oxidizers (Potassium Permanganate is often used for disease treatment and water clarification in ponds and aquariums). However you would not want your fish living in a constantly oxidizing environment for long term fish health, rather you would want your fish in a balanced redox environment which includes a Reducing environment where free radicals are not damaging the cells of your fish and causing problems with Osmoregulation.
Further Information: Fish Osmoregulation
An oxidizing environment is what you get with a positive Redox of generally +350 mV and is OK (& necessary) for certain periods such as during disease treatments, however you would not want to keep your fish in constant medication any more than in a constant strongly oxidizing environment (PLEASE read the section about Natural Redox including the quote and outside Redox for a better understanding of this concept)!
Another IMPORTANT consideration is a healthy Redox affects the electrolyte balance in your aquarium. Calcium as well as Magnesium are both important reducers when positively charged, however they are both easily oxidized as well (please see the chart in the Redox Potential Basics section).
So for proper reduction, these elements, or at least their positive ion charge need to be replaced on a constant basis (read further in this article for more on this subject).
The Redox Potential explains a lot of the results I was getting as the fish have a better ability to resist a disease sometimes simply by having a healthier immune system and osmoregulation.
This pertains to a Balanced Redox potential (which includes a proper magnetic charge in the water) that I have found a properly installed and constructed UV Sterilizer aids in maintaining as well as proper mineralization of reducers and constant replenishment of these minerals, such as calcium, and regular water changes. that lower nitric acid and DOC levels (dissolved organic compounds).
Further Reference: Aquarium Cleaning, reasons, methods
What got me started in researching this topic was that I noticed and documented, differences in health, vitality and especially disease resistance within different aquariums.
I mostly used goldfish for these tests, with regular water changes, UV sterilizers, added minerals/ electrolytes, such as Wonder Shells or similar methods/products.
The goldfish had fewer instances of general diseases as well as infestations such as Ich, Anchor Worms, and other problems with the constant replenishment of mineral cations and the use of correctly installed efficient UV sterilizers which contribute to balanced Redox. What is/was noteworthy is that the UV Sterilizers were not even run within the parameters that would kill Ich outright, yet I still was observing lower instances of Ich!!
WHY? The answer is simple in that the aquarium had a more healthy Redox Balance that aided in the fish' own natural immunity and resistance to Ich!
PLEASE NOTE; many UV Sterilizers now marketed for under $50 CANNOT perform Redox reduction due to their poor dwell time, low cost medium pressure UV bulbs, and other factors, these are at best clarifiers and should NEVER be purchased unless that is all you desire from your UV!.
Further Reference: Actual UV-C Emission from a UV Bulb
This shows that the health of aquarium fish can be directly aided by positive mineral ions/magnetic charge of the water and a properly installed "true" UV Sterilizer, not just by the killing of potential disease pathogens, but also by the effect UVC has on the Redox Balance of an aquarium.
I have been observing many aquariums of "ordinary" fish, both with and without UV Sterilizers (keep in mind that some UVs are useless by design and installation), and the goldfish with every other factor equal (such as mineralization and water changes) that had a UV Sterilizer installed, were generally much healthier.
A High Dwell Time UV Sterilizer works similar to the ozone layer in our upper atmosphere (except in reverse); although the UVC emitted by the sterilizer is itself an oxidizer, the interaction of the UVC inside the unit with oxidizers such as ozone is such that the UV Sterilizer REDUCES these oxidizers and free radicals as well as potentially magnetically charges the water.
This was confirmed by Dr. Mamoon Kundi in an email he sent me as per his work using UVC to balance Redox in human studies, and thus improving immune function
For those interested in checking this out, simply add potassium Permanganate into a tank with a UV Sterilizer and one without. The tank with the UV Sterilizer clears MUCH quicker!
If your aquarium has a high bio load, the addition of a properly installed UV Sterilizer can actually temporarily add too much Redox Reduction resulting in a darkening of water color until the Aquarium Redox balances again.
Please Reference/Read: Aquarium Bio Load
In further research I noted that a proper Redox Potential improves the health of humans AND fish.
A Redox Potential in the -200-400 mV range in human studies has been shown to have the same affect as anti-oxidant preparations as Vitamin C, and many others.
In medical studies, the enhanced oxidizing environment can facilitate the binding of pathogens or antigens to effector cells (a type of lymphocyte that are actively engaged in secreting antibodies) leading to a hyper-responsive innate immune system.
Previous work has shown that an oxidizing environment leads to enhanced release of super-oxide and nitric oxide, activation and translocation of nuclear transcription factor and enhanced production of cytokines (proteins and peptides that are signaling compounds produced by animal cells to communicate with one another). The creation of a reduced environment by addition of antioxidants blunts all of the above primary responses of the innate immune system.
Back to my many tests with goldfish tanks over several years in the 1990s; I ran these tests with many different filters and combinations there of.
Cleanings were consistent every two weeks with about 25% changes of water via a Gravel Vacuum. Feeding was performed at the same intervals with the same food (at that time Hikari and Spirulina 20), and all the tanks had the same number of goldfish at as close to the same size as possible.
I found the tanks with the Under Gravel Filters performed the worst (and not just in Redox) due to their tendency for DOC (Dissolved Organic Compound) buildup which results in high amounts of Nitric Acid production.
UG Filters performed better when combined with a UV Sterilizer and another filter such as a canister filter, however the tanks that performed the best did not have UG filters, rather a combination of two filters (generally a Sponge Filter or Fluidized Filter were part of this combination) AND a UV Sterilizer.
Some of the tanks were maintained with added minerals/electrolytes, some were not.
The best results as per long term health were achieved where minerals cations (positive mineral ions) were added on a constant basis vs. methods that required weekly or similar dosing requirements or non minerals at all.
That said, please read the rest of the article before I over sell any one on a UV Sterilizer, Mineral Blocks (such as AAP Wonder Shells), or drip mineral applicators (products such as SeaChem Replenish can be mixed with water and dripped into the aquarium). As often good aquatic husbandry is a major factor in a healthy Redox Potential (balance).
Another interesting aspect of Redox potential is the correlation of a certain Redox level and the growth of Blue Green Algae (Cyanobacteria) in Aquariums and lakes. This is an on-going study however Redox does SEEM to play some role in the aquarium and lake “plague”.
For more information about this, I recommend reading this article: Blue Green Algae (Cyanobacteria) in Aquariums; what it is and how to control it.
Currently this is just an opinion/theory though. Back To Top
Including Human Studies:
Over geologic time, abiogenic, biogenic, and anthropogenic deposits were accumulated in rivers, lakes and seas. TERMS:
*Abiogenic = not biological in origin
*Biogenic = produced by living organisms
*Anthropogenic = processes that are derived from human activities
Simultaneously all three of these processes proceed to self-purify natural water on the basis of the chemical reactions of oxidation and reduction.
Living organisms such as fish are adapted to NOT "perfectly clean water", but to ecologically clean water with definite content of organic and inorganic compounds, micro-admixtures, Magnetized ions, and even bacteria or saprophytes (saprophytes are an organism that grows on and derives its metabolic energy from dead or decaying organic matter; such as most fungi).
The range of mentioned components of ecologically clean water is the integral result of oxidation and reduction self-purification of water.
At the initial stages of this natural cycle, toxic hydrophobic organic compounds (molecules that are repelled from a mass of water) are oxidized to the hydrophilic form, which is a molecule, or portion of a molecule, that is typically charge-polarized and capable of hydrogen bonding, enabling it to dissolve more readily in water than in oil or other hydrophobic solvents.
These are characterized by the better biological compatibility.
Energy of oxidation by way of degrading organic compounds is absorbed during reduction chemical transformations. Excess ions of the heavy elements transform into insoluble, inert, nontoxic forms. The concentration of ions of light elements are then stabilized.
Water organisms, live in such water, and land animals drink it.
Spring waters, which are considered to be the most clean, according to the ecological criteria, are filtered through the rocks and subjected to the oxidation and reduction, sorption and catalytic influence.
As a rule, they are mineralized and include non-volatile organic substances, which are detected by the permanganate oxidability (expressed by oxidability by potassium permanganate and potassium dichromate).
Put more bluntly; only water that has been naturally filtered by percolation deep into the earth, heated under pressure to super steam at the mantle and re-imprinted by the clays, gravels and minerals that it passes by on its way to the surface at 4C is fully mature and full of useful electromagnetic energy.
ORP can change rapidly, and Redox potentials above 400 mV are dangerous to life.
Good quality water for life is lower than 350mV, and water of lower than 100mV is effective for disease healing purpose when the part of body is particularly oxidized (harmed) by disease.
In tests using electrochemical purification, water keeps its initial neutral values of pH, but ORP (Oxidation Reduction Potential) of water shifts toward the negative (electrode or reduction) values.
The resulting purified water obtains the antioxidant properties with characteristics of pharmacological activity close to the properties of the antioxidant preparations (a -tocopherol, b -carotene, vitamin C etc.).
In cases of dilution of polyvitamin preparations in electrochemically purified water, the ORP of mixtures is decreased by approximately 200 - 400 mV in relation to the control solutions with non-treated drinking water.
The above partially explains how a proper Redox Potential improves the health of the fish or other aquatic organisms as I have observed.
Bringing this back to my observations of goldfish aquariums; All aquariums with the same filtration (canister filter with sponge filter), the same feeding schedule and food, even the same basic goldfish (a mix of Ryukins and Orandas); The aquariums with the quality, properly installed UV Sterilizers (again assuming proper dissolved oxygen levels) not only had less incidence of disease, but general health, appetite, vigor, growth, and water clarity were all improved.
Here is a Quote about pH vs. Redox:
Traditionally we have judged the properties of water from the standpoint of pH, in other words whether water is acidic or alkaline.
According to Dr. Yoshiaki Matsuo PhD., the inventor of the Ionized Water unit: "In my opinion, Redox potential is more important than pH. The importance of pH is over emphasized.
For example, the average pH of blood is 7.4 and acidosis or alkalosis are defined according to deviation within the range of 7.4 +- 0.005. But nothing has been discussed about ORP, or oxidation-reduction potential."
A further point on human studies shows this:
“Dr. Uchiyama, working at a general hospital in Japan, conducted a complete medical checkup with his 871 clients.
The result was 92 had normal results (judged healthy) and 279 requiring further consultation or treatment for their health (judged potentially sick).
He measured OPR of all of their urine.
It was found that many healthy clients showed ORP voltage of +50 to +74 and clients judged unhealthy showed +100 to +124. Healthy persons tended to have lower voltage of ORP, less oxidation potential in their body.”
I have mostly discussed Redox Reduction and its misunderstood importance, however there does need to be a balance between reduction and oxidation for proper chemistry within a fish or most all living animal organisms.
The best current research seems to indicate a Redox reading of approximately +125 (freshwater) as a balanced Redox with optimum electromagnetism of the water.
However Redox Potential is often in “flux”, so I personally believe following healthy aquatic husbandry methods (that consider the affect on Redox) is an aquarists best bet in maintaining this balance. This includes a higher Redox (as high as +350) when oxidation is necessary due to high organic decomposition.
Bio Chemistry as it relates to Redox Balance:
There are enzymes within a body that are reactive oxygen species (ROS) and others that are reactive nitrogen species (RNS). A disturbance in the oxidation–reduction state of the cell, in which ROS production exceeds antioxidant defenses, is called oxidative stress.
By analogy, nitrosative stress is an impairment in nitric oxide (NO) signaling caused by increased amounts of RNS, which may be caused by, or associated with, a disturbance in the Redox state. As discussed earlier, free radicals are highly reactive molecules with unpaired electrons.
Free radical chemistry is the underpinning of 2 broad classes of signaling molecules in biological systems: ROS, which are reactive intermediates of oxygen metabolism, and a closely related group of RNS.
The forms of ROS that are relevant in biological systems include the superoxide radical (O2•–), hydrogen peroxide (H2O2), and hydroxyl radical (OH•).
RNS of biological importance include NO, low- and high-molecular-weight S-nitrosothiols, and peroxynitrite (ONOO–).
Superoxide and other ROS are produced in the mitochondria during oxidative phosphorylation as a normal byproduct of aerobic respiration in fish (and other animals).
Superoxide is formed by the 1-electron reduction of molecular oxygen, resulting in a free radical. However ROS are not intrinsically destructive; on the contrary, increasing evidence shows that they play necessary roles in normal signal transduction.
In low concentrations, they are implicated as second messengers primarily through inhibition of phosphatases, acting downstream of effectors such as platelet-derived growth factor, epidermal growth factor, tumor necrosis factor agonists, and interleukin.
In higher concentrations, however, they take on pathophysiological roles. ROS affect the oxidative modification of diverse molecules, including DNA, proteins, lipids, and sugars, potentially leading to toxicity.
The problem begins when either ROS (oxidation) or RNS (Reduction) get out of balance and unfortunately in closed aquarium or pond systems this is all too common.
An aquarium with poor circulation and low oxygen levels can swing towards poor oxidation, while more commonly Reduction is halted by the fish’ body inability to reduce these superoxides.
Reduction is dependant on production of RNS; NOS3 (endothelial NOS) are found in a variety of cell types and are regulated by binding to calcium and calmodulin (calcium-binding protein expressed in all eukaryotic cells).
NOS2 (inducible NOS), on the other hand, has very high baseline affinity for calcium and calmodulin; therefore, its activity is effectively independent of calcium concentration. The importance of calcium in this reaction is often missed by most aquarists based on the many emails I get and comments I read on many misinformed aquatic forums.
As well, the reduction side of this equation can also be interrupted by the oxidation of other reducing chemicals such as ascorbate (vitamin C) and reduced thiols, especially glutathione (a tripeptide). These reduced chemicals become temporarily oxidized when they interact (giving up of their free electrons) with oxidizing agents and oxidizing free radicals.
Further Reference: "About Glutathione
A more basic aspect of Redox Balance is the water we use can have a direct impact as well.
The water we use, whether from the tap or Reverse Osmosis/De-ionized this too can affect your Redox Balance, sometimes negatively. Generally speaking tap water if only altered with chlorine or chloramines may or may not have the necessary mineral cations to bring a poor Redox back into balance.
The use of RO or DI water, while a very practical way to improve and control water parameters (especially with soft water freshwater species or reef aquaria), one should note that the necessary mineral positive mineral ions (cations) are usually gone (removed). The resulting excess oxygen and more acid water is often way too high of an oxidizing environment.
For this reason it is often important to re-minerals these water sources with products such as SeaChem Replenish or Wonder Shells. Product Resource: TMC Aquarium Reverse Osmosis Water Filter System Back To Top
REDOX POTENTIAL (BALANCE) AS IT PERTAINS TO AQUARIUMS:
There are multiple mechanisms for maintaining a good redox balance from a good oxygen exchange for oxidation to mineral ions and certain light energy for important reduction.
Another way to look at the Redox Potential in aquariums is to the relation of waste particles and acid production, as well as dissolved oxygen and most importantly depletion of key important elements.
The more waste, the less Redox Potential (ORP) due to more nitric acid production and the depletion of key elements, but this is an over simplification as there is much more to it than this.
You really need to look at the electrolyte balance in your aquarium.
Calcium, as well as Magnesium, are both important reducers, however they are both easily oxidized as well (see the graph in the Redox Basics section). So for proper balance, which includes reduction, these elements or more importantly their "electrical charge" (positive ions/cations) need to be replaced!
Obviously high organic wastes also require an input of oxidation (higher Redox for Redox balance), but this should not be ongoing due to a poor balance of reducing to oxidation because of the lack of redox reducing mechanisms as well as a bio load the aquariums system cannot support.
This is good reason to not overstock and aquarium, as there is a point where by it is impossible to balance your aquarium Redox other than for short term.
Simply put, these factors have the most affect in Redox Balance Maintenance
Water Changes; this is the most obvious and simple, however this is often not sufficient and sometimes the new water used does not have adequate mineral ions (especially if RO water is used even in part), so supplementing with mineral replenishers, such as SeaChem Replenish, Wonder Shells, etc. (even during water changes may be necessary). Please note that performing inadequate water changes or worse, only topping off water for evaporation does not adequately replenish important redox reducing ions of calcium or magnesium. Most any aquarium is going to utilize these ions at a far higher rate than simply adding “fresh” water or even some water changes will ever replenish.
The end result of such poor maintenance procedures will result in climbing GH readings, yet your aquarium (or pond) ability to maintain a healthy Redox balance will suffer.
Addition of positive mineral ions in between water changes, especially during times of stress or high bio loads can increase the Redox Reduction to counter oxidative affects on fish.
Lack of positive mineral ions during stress can be a factor in a Columnaris outbreak.
Further Reference: Aquarium Columnaris
Use of a UV Sterilizer which impacts Redox Balance in a different way than water changes or additional minerals;
The UVC irradiation destroys destructive oxidizers and aids in establishing the proper balance of electromagnetism of the water column which can otherwise add oxidative stress to fish. However the use of Ozone Generators does NOT accomplish the same results with Redox balance, despite similar results in sterilization (I found this stated in some very confused articles and forum posts I have read).
Recently reviewed and updated tests have also shown the positive benefit of near-infrared to infrared light in the improvement of Redox Reduction and wound healing.
Again, this is now a proven fact that has aquatic implications for good lighting that hits these nanometer spikes. Generally within 5500K to 6700K lighting, although specific 'Red' lighting can help too, such as the TMC Flexi-Red LEDs or TMC Colour Plus LEDs. Product Resource: TMC Aquarium LED Lights; Including Flexi Red & Colour Plus
Important; what is often missed, is that although you may test and, for instance find, high calcium levels in an aquarium via a GH over 300, this does not necessarily mean you have any Redox reduction as I should point out that very basic fact of Redox reduction is the donor (such as calcium) transfers electrons to another substance, and is thus, oxidized itself. This is VERY key, meaning your GH test (or Calcium, Magnesium, etc tests in saltwater) may tell you that you have ample or even too much calcium, HOWEVER these calcium molecules may have already given up their electrons to other molecules such as fish cell molecules so as to achieve a state of balance in aquarium Redox.
This again is where many will claim that their calcium or other minerals are high enough or even too high (as many still get INCORRECTLY stressed about the high GH brought on by Wonder Shells, totally missing that these mineral blocks are constantly reducing the water via their donation of electrons!).
This is also where water changes and UV Sterilization also help as these processes constantly balance out Redox.
Since water changes (which also aid in oxidation, which is the other side of the equation) can only be done in intervals.
Unless you have a flow through system, the use of mineral blocks, or other water conditioners as well as UV Sterilization to keep a more steady flow of electrolyte donation is important.
With the above statements in mind, one must look at two VERY basic organic chemical reactions that occur in an aquarium;
As stated in the opening section of this article; “oxidation of carbon to yield carbon dioxide”, this describes the process of nitrification or in other words the breakdown of organic wastes by Autotrophic nitrifying bacteria into ammonia and nitrites. The higher the bio load, the more of this process is occurring. So it is imperative to replace elements such as negatively charged ions of calcium, magnesium, etc that are oxidized due to this process.
This is where many aquarists “miss the boat” as per reasons for water changes, replenishing minerals, or other Redox Reduction processes that will balance this out.
This is also why tanks without good ionized mineralization, UV Sterilization, water changes, etc. will often be MUCH less healthy as per disease resistance.
Reduction as also stated in the opening section: “reduction of carbon by hydrogen to yield methane (CH4)”, this describes the de-nitrification of nitrate as it reduces to nitrogen.
This process is more common in Marine tanks but can take place in freshwater in certain places where methane production is not an issue such as filters with anaerobic filtration that allow methane to escape (volcanic rock & SeaChem Matrix provide a good place for this process). Also the growth of plants, especially with strong roots in a sandy substrate allows for de-nitrification/Redox reduction.
This is an area where Veggie Filters in Ponds shine in their ability to maintain excellent bio parameters. This also to a lesser degree shows where some green algae growth is not all that bad.
Further Reference: Pond Veggie/Bog Filters
All this said, Reduction generally de-nitrification processes CANNOT keep up with oxidation processes necessary for breakdown of organic wastes, which is why help is needed via water changes, mineralization, UV Sterilization, etc.
This is where many naysayers of products such as Wonder Shells, or UV Sterilizers TOTALLY miss the point as to how much they can improve water quality.
This is also how the use of products such as Volcanic Rock or SeaChem Matrix can also indirectly affect Redox.
Put another way, there is certainly a time and place for a high Redox (oxidation) as lower oxygen levels from many causes such as high organic decomposition is generally not desirable and this will lower your Redox oxidation side of the equation.
This is not what I recommend as a means of a reducing Redox environment. However to not have the proper reducers or creating a highly oxidative environment is also not good for long term fish health.
The Redox Potential is always going to be in flux and as yet no scientific equilibrium has been established here.
Maintaining reducers such as Calcium and Magnesium in your aquarium is just as important as proper levels of dissolved oxygen (which raises Redox).
There is evidence both anecdotal and controlled that proper levels of calcium and other anti-oxidants such as Vitamin C (along with other healthy water parameters) will prevent and even cure Hole in the Head disease (HITH). Redox is an important parameter here.
Further Reference: Aquarium Answers, about Hole in the Head Disease
As stated earlier, Redox can be more important than pH, there are definitely correlations to pH and the Redox effect on pH.
But you cannot make the assumption that if you have a pH of 8.0, that you have good reduction. Just like with GH, where your GH is high, you can still have low pH.
The bottom line is that there are relations between Redox, GH, pH, and even kH, but these are still individual water parameters.
Also as noted in the beginning of this article, this is not a parameter to stress over, HOWEVER, Redox reduction should NOT be blown off as many anecdotal/uninformed commentators do in some aquatic forums. The more I have studied and observed in this subject, the more I feel it should not be ignored!
Effect on Fish:
Active oxygen molecules, or free radicals, are produced in the water and the fish’ body. They are extremely reactive and can also attach themselves to normal, healthy cells and damage them genetically.
These active oxygen radicals steal electrons from normal, healthy biological molecules.
This electron theft by active oxygen oxidizes tissue and can cause disease; these are proven facts!
This why the constant hammering by some un-informed aquarists (such a popular planted aquarium guru) against UVs, too high a GH (which is not always a good indicator of electrolyte balance anyway), and even the use of mineral blocks (such as Wonder Shells) is ludicrous!
Your GH may test higher than desired but in actuality is maintaining a healthy Reducing Redox via the reducing properties of positively charged calcium, magnesium, etc.
Further Reference about Calcium: Calcium (Facts about Calcium, an essential reducer)
Effect on plants:
In a controlled test conducted with terrestrial plants; plants treated with magnetized water (basically Redox Balanced Water) reacted in a test, with a growth in the order of 20% to 40% bigger than the plants treated with regular water.
While no test has been conducted with planted aquariums, it is not rocket science to draw conclusions from this study and apply this to a planted freshwater aquarium and the effect of Redox Balance on plant growth!
Reference: Water Information & Conductivity
Simple Redox Test
A simple test of Redox can be performed using Methylene Blue and any reducer such as powdered Wonder Shell.
Simply add enough Methylene Blue 8 oz. of water to turn the water a brilliant blue (usually one drop).
Then add about ½ teaspoon powdered Wonder Shell to the 8 oz. of water and stir. The Methylene Blue will dissipate due to the reducer.
Taking this test a step further into the real world; again add enough Methylene Blue 8 oz. of water to turn the water a brilliant blue (again one drop), this will be the control color. Then take out 8 oz. of aquarium water and add the same amount of Methylene Blue as in the control glass of water.
If the color dissipates at all (even the slightest) you probably have a balanced Redox with at least some reduction. Expect to see little color change in a healthy aquarium, although absolutely no color change MAY indicate too much oxidation, while any more than a subtle change may indicate too much reduction.
More about Methylene Blue: Aquarium Medications Part 3, Methylene Blue Back To Top
REDOX AS IT PERTAINS TO STRESS
In biological systems, the Redox Potential must be kept reduced to perpetuate the life process. In other words, the concentration of DHA (an oxidized form of ascorbic acid), must be kept to a minimum.
During injuries or stress which expose body tissues to atmospheric oxygen or disease, several reactions are triggered in polyunsaturated fatty acids (PUFAs) present in cellular membranes which produce hormones called prostaglandins that repair damage.
Under oxidizing stress (injury or disease) or impaired ability to manufacture NADH (aging or disease), the concentration of DHA can rise as the redox potential slips. This is a potentially life-threatening state for fish or any other animal.
The initial rate at which the redox potential falls as DHA increase is initially slow, however as DHA increases further, the redox potential falls faster, becoming progressively more antagonistic to the metabolic processes of life. Eventually; if the process is not stopped, the fish (or any animal organism) slides down into death.
This is why even prolonged stress (such as constant harassment by tank mates) can lead to illness and even death and why under stressful conditions having ample reducers such as positively charged calcium ions or TRUE UVC sterilization is so important!
Proper water changes with ion balanced clean water (electrolytes) with a GH of at least 100- 200 (GH will supply many important reducers such as Calcium & Magnesium) and with a kH of at least 50-100 ppm (for control of nitric acid production). A proper Reducing/Balanced Redox is another reason for water changes and is also a major reason to not use drinking water intended for human consumption unless it is properly re-mineralized.
Removal of organic mulm during cleanings is important as this leads to nitric acid production and high DOC (dissolved organic compounds) which are major contributors to a poor Redox Balance. If your water changes are not effective in removing all organic mulm, consider a re-circulating vacuum (such as an Eheim Sludge Remover) that can drain and then continue to remove mulm that is easily emptied from the micron filter. Product Resource: Eheim Sludge Remover; Aquarium Organic Debris Removal Tool
Also ponds with “flow through” or spring fed water sources will maintain a good Redox Potential by virtue of the constant addition of fresh, clean and mineralized water, which is why many lakes will become less “healthy” during the late summer months when stream that feed them “dry up”.
Good aquarium circulation This aids both sides of the Redox equation, although more so the oxidation side.
A reasonable supply of dissolved oxygen provided by diffusers on power heads, internal filter, air stones, spray bars on the returns of canister filters, etc.
Just make sure you are doing a good job of breaking the surface tension of the water, as this is where gasses, including oxygen are exchanged!
Adequate Calcium, Magnesium, sodium, and general electrolyte levels, THIS IS VERY IMPORTANT!
As noted earlier, this is an on-going process with a starting point to maintain a GH of 100 to 500 ppm (less for soft water fish, higher yet for African Cichlids and Marine).
This is an incomplete picture as recent evidence shows that you may have an adequate amount of Calcium as per your test, but this calcium has given up many of the available electrons and is not aiding in your Redox balance.
This is why using mineral blocks or similar concepts is so important. This also further disproves the point of many old aquarium myths about too high of a GH, as what your test is measuring may not be the whole picture since it cannot measure positive mineral ions that may or may not be present.
AAP Wonder Shells are very useful since they add important mineral cations on a constant basis. As well, products such as SeaChem Replenish, Instant Amazon, or Aragamix can be mixed with water and dripped into aquariums to achieve constant positive mineral ions. However I have not found that the use of crushed coral will dissolve at a rate to supply enough of these minerals to have much affect on Redox Balance.
A UV Sterilizer is one of the more predictable and proven tools here (when CORRECTLY installed with a Level One UV Sterilizer), but also not a cure all to otherwise poor conditions.
UVs work two ways in my research; [A] they morph oxygen (O2) molecules into Ozone (O3), the O3 quickly degrades, the UV then [B] transfers electrons to substances, thus reducing.
As a side note it is the Ozone layer that blocks many harmful UV rays from reaching the Earth, this is due to the reaction of UVC and Ozone high in our atmosphere, so by using a UV Sterilizer (which has safely contained UVC irradiation), you break down radicals such as Ozone in your aquarium.
Good Lighting, Although not as common a problem for most marine aquarists, especially reef keepers as these aquarists usually have (& know the benefits) of good lighting, in freshwater aquariums this is often a contributing factor to a poor Redox (and to other problems as well).
The reasons are admittedly not completely clear, however from my observations, tests and research, I believe correct lighting plays a role similar to UV Sterilization as explained above, when lighting with poor PAR qualities which are generally found in lights with approximately 6400 Kelvin temperatures.
My suspicions are that although PAR has been scientifically established to be important for plants, it may also play an important role for fish as well (both in electromagnetism of the water and similar to how humans derive the benefit of vitamin D production from sunlight).
As noted earlier, the red spectrum has also been recently proven to aid in Redox Reduction and healing of wounds, so this is another reason to maintain good lighting, not just for your reef inhabitants or planted freshwater aquariums but for your guppies, goldfish, etc.!!
Use of water conditioners (for use in chlorine/chloramine removal) during times of stress (especially oxidative stress) such as SeaChem Prime which are mostly all Reducers.
However these products only temporarily reduce Redox and are not a long term solution. It also should be noted that aquarium water conditioners will often cause temporary cloudiness of aquariums due to their strong reducing abilities, however this cloudiness is short lived in healthy aquariums. Product Resource: SeaChem Prime; Water Conditioner, Reducer
Driftwood; make sure you soak all Mango Wood or Drift wood for several days in a solution of 2 tablespoons pure salt to 2-5 gallons of water to leach out impurities. Even then, if you continue to have problems remove the wood. Over use of peat can also cause similar problems.
CO2 generators if not kept at a balance can also cause problems with the Redox Reduction abilities, this is rare, but worth considering.
A good link to help here is: Measuring CO2 levels in a Planted Tank
An abundance of organic mulm in filters or substrate. This can be wet/dry filters, canister filters, and very often in a poorly managed "live rock reef" and sand in a reef aquarium.
I will also note as per my many tests with goldfish aquariums, I found Under Gravel Filters the worst offenders here with high production of DOC (Dissolved organic compounds), and even with UV Sterilizers these tanks were more difficult to maintain a balanced Redox environment in.
Check your cleaning procedures as well.
This mulm or DOC has a direct impact on your aquarium bio load, resulting in a fragile Redox Balance where by any change to this balance, often a sudden increase in Redox Reduction by the addition of a properly installed UV Sterilizer results in noticeable change to water quality.
Please Reference/Read: Aquarium Bio Load
A lack of electrolytes (positively charged mineral ions), as mentioned earlier, 'AAP Wonder Shells' or dripping products such as Aragamix, SeaChem Replenish, or similar can help here, BUT they are not a cure all for other problems.
A tank with high nitrates (nitrates are a mild oxidant) will also tend to be high in nitric acid (but not always); a properly cycled tank is important! This also usually occurs with high DOC levels (dissolved organic compounds), regular water changes that remove organic mulm are important here.
Improper use of an Ozonizer (Ozone Generator) can defeat the purpose of using a UV Sterilizer by allowing ozone into an aquarium and thus raising the Redox to levels too high for long term fish health.
An Ozone Generator MUST be used with a Protein Skimmer that is capable of containing ALL ozone, such as the TMC V2 Skim Protein Skimmer. This is not the case with many Protein Skimmers, and even the TMC model or others similar must be properly monitored when using ozone. Product Resource: TMC V2 Skim Pro Protein Skimmer
As noted earlier, good lighting and the addition of a UV Sterilizer can play an important role for a balanced aquatic Redox Potential as newer studies have proven that UV Sterilization increases immunity by adding electrons and balancing the essential electromagnetism of the water.
Although less conclusive at this time, high PAR lighting (usually found in lights with an approximate Kelvin of 6500 K), also aids in replenishing reducing electrons due to depleted reducing minerals. Product Resource: True UV Sterilizers Capable of improving Redox Balance
This is a relatively unexplored area of fish keeping, and there is still a lot to be learned here and I have to admit having to change my opinions based on newer evidence (I too thought that only a high positive Redox should be maintained), my research is still ongoing and I try and read whatever I can on this subject, especially from outside the aquarium hobby, even if it may not fit with theories I hold.
In fact this is now probably my most researched subject, with many outside sources cited here. As well, I have received emails from outside the aquarium community from medical researchers congratulating my conclusions as to Redox by citing current research and then applying it to aquariums.
Unfortunately some otherwise experienced aquarists in their writings or anecdotal forum comments fail to look at the research that has gone on the subject of Redox and stick to their old tired theories about Aquarium Chemistry and the affect of Redox thereon much the same way many continued to claim the "earth was flat" even when proven incorrect.
It is important to note, that just because many aquatic articles report only the importance of an oxidizing Redox, this does not make it true, science is not a vote!.
It really is not that difficult to read outside (non aquarium hobby) articles that show otherwise. This is an unfortunate side of the aquarium hobby is that many will pass around old tired so-called facts as truths without reading anything that contradicts there theories masquerading as fact.
I read a recent article that is easily found in search that is admittedly well written dealing with Aquarium Redox, with a good explanation as to what Redox is and more, however this article still chooses to repeat much of the same tired old information about only the positives of the oxidative side of the Redox equation, missing the evidence that the reduction side is also VERY important to a healthy Aquarium Redox Balance (I noted that the sources this particular article sited were all more than 15 years old which may explain much of the out of date information). Ignoring both sides of this equation is akin to acknowledging the importance of oxidation in the breakdown of dead animal and plant material, yet to ignore the fact that if this oxidation process were to continue unabated without reduction, we and all other living organisms would be consumed immediately!! This simple but important point must be understood.
The basics of Redox are really not that hard to understand and are easily applied; that is knowing that a high bio load can have a downward effect on a good Redox while water changes, additional mineralization, UV Sterilization and more can have positive effect on Redox.
Simply put, think of a Redox Balance of a magnet with opposite poles, and with without this electromagnetism of the water which makes up 90% of living tissue, the health of any living organism be it a fish, or aquatic plant will be affected!
You must realize that these electrons necessary for balancing Redox are often used up and the incorrect assumptions often made about GH, UV Sterilization simply do not fit the evidence!
I will also note, the more complex aspect/equations of Redox are certainly worth learning (I am still trying to “grasp” them all), however I would not let it frustrate you if they are difficult to understand.
Finally; achieving a Redox of about +300 to +100 mV for marine or +200 to -200 mV for freshwater are the raw numbers we are aiming for. (as per the graph in the background section).
However if you have read this article thoroughly including the outside links/website other than my material, you will know that this is an extreme over simplification as there are times for higher and lower Redox readings!
In other words, think of your Redox as constantly in flux with there certainly being times for a high/oxidizing Redox, but a +350 or higher Redox should not be the norm for most healthy aquariums or ponds. Back To Top
Here is a quote from the above article;“Many aquarists have been lead to believe that ORP is a measure of water quality or purity. Manufacturers selling ozonizers and other oxidizers (like permanganate) have been especially keen to present that idea.
But is it really true? Is a higher Redox indicative of "purer water" even when that Redox is manipulated artificially by adding strong oxidizers? Or is such an addition analogous to an air freshener that masks odors? I don't know the answer, but I think that aquarists should ask the question, and hope to hear useful answers before adding such materials to their aquaria.”
This statement is where many aquarists have gone wrong in my opinion, A positive Redox is NOT a measure of water quality, but at least a Reducing Redox has more potential for a healthy aquarium.
(These are MUST reads in my opinion)
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