  
THE REDOX POTENTIAL (ORP) IN AQUARIUMS (& PONDS);HOW IT RELATES TO PROPER AQUATIC HEALTH Effect of water changes, DOC, UV Sterilization, mineralization on a healthy Redox Balance |
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THE REDOX POTENTIAL (ORP) IN AQUARIUMS (& PONDS); HOW IT RELATES TO PROPER AQUATIC HEALTH Effect of water changes, DOC, UV Sterilization, mineralization on a healthy Redox Balance |
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By Carl Strohmeyer Updated 5/7/09 REDOX (REDOX POTENTIAL) BASICS (OXIDATION POTENTIAL, ORP):  Although not a well known process among many aquarists, 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.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, UV Sterilization, and proper positively charged mineral levels (such as Calcium and Magnesium). (Please click on the picture above/right to enlarge for a better view) *Oxidation describes the loss of an electron by a molecule, atom or ion Example: Redox processes such as the oxidation of carbon to yield carbon dioxide. *Reduction describes the gain of an electron by a molecule, atom or ion. Example: The reduction of carbon by hydrogen to yield methane (CH4). Another example: Calcium or Magnesium which initially are composed of positively charged atoms immersed in a sea of movable electrons may have given up all possible electrons to cells 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 will suffer. 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 plates become exhausted, the battery is no longer any good. 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:Oxidized water with its Redox potential of +700 to +800 mV is an oxidizing agent that can withdraw electrons from bacteria and kill them. The oxidized water can be used to clean hands, sterilize utensils, and treat minor wounds. Here are a few oxidizers: ozone (O3; Oxidation potential= +2.1), hydrogen peroxide (H2O2; Oxidation potential= +1.82), chlorine (Cl2) and chloramines (NH2Cl). Reduced Water: 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 transfer electrons to another substance; Magnesium, Calcium, Sodium, and the process of Photosynthesis involve both oxidation and reducing. As one can see from the graph that 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). One more basic generalization to consider before moving on in 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. However, in natural water (generally spring water), acidity of minus ions and alkalinity of plus ions can coexist (more about this in Natural Redox). It is important to note that Aquarium Redox can be a complex subject with some basic principles to also understand, however this is a subject that simply 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  )BACKGROUND: This article is based on studies about the Redox Potential as it corresponds to humans and all fish and animals. 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 anecdotal aquarium articles (these articles usually just take bits from another article without any real research, often with old ideas being simply regurgitated), this research then has to be properly applied and a good aquatic article can help here. Originally my statement 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”. However 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 anecdotal aquarium keeping beliefs (such as so-called correct GH and positive vs. negative Redox). I have also had to change my opinions about this subject based on newer evidence. One 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 (as of this writing, both oxidizing AND the less known reducing Redox play important roles in fish health). All this said, maintaining a good Balanced Redox (for both saltwater and freshwater) can be as simple as good aquatic husbandry: water changes, proper electrolytes and minor elements in the water, using simple reducers such as Sodium Thiosulfate, Calcium and Magnesium when necessary.. 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. 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 (oxidation); Bleach and Potassium Permanganate are oxidizers (Potassium Permanganate is often used for disease treatment an water clarification is 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 Reducing environment where free radicals are not damaging the cells of your fish and causing problems with Osmoregulation. An oxidizing environment is what you get with a positive Redox and is OK (& necessary) for short periods such as during disease treatments however you would not want to keep your fish in constant medication any more than in a constant 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, however they are both easily oxidized as well (please see the chart in the Redox Potential Basics section). So for proper reduction, these elements need to be replaced (read further in this article for more on this subject). What got me started researching this was I have noticed and documented differences with aquariums (I mostly used goldfish for these tests) with regular water changes, UV sterilizers, added minor elements (such as Wonder Shells) and electrolytes, but was not sure why health, vitality and especially disease resistance were improved. The goldfish had less incidence of such general diseases as well as such infestations as Ich, Anchor Worms and similar which UV sterilizers cannot truly eradicate due to difficulty killing them in the UV itself and that parasites such as Anchor Worms do not get readily caught up in the water column. 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 slime coat). This pertains to a Reducing Redox potential that I have found a properly installed and constructed UV 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). 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 such 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 markedly reduced environment by addition of antioxidants blunts all of the above primary responses of the innate immune system. This shows that the health of aquarium fish can be maintained by a UV Sterilizer not just by the killing of potential disease pathogens, but by the maintenance of a proper Redox Potential. I have been observing many aquariums of such "ordinary" fish as goldfish, 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. The 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. 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! See this outside article for UVC/UVB healing therapies in humans now being proven in tests! Oxygen Healing Therapies with UVC I will also note that the aquariums with a reducing Redox had the electrolytes present as tested via GH & KH ( SeaChem Buffer, & Wonder Shells are a good source), and regular water changes which also resulted in lower nitrate levels (40 ppm or less for FW, 20 ppm or less for SW). 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 a constant of 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) do 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 AND a UV Sterilizer. Some of the tanks were maintained with added minerals/electrolytes, some were not. Those with performed better in long term health and showed more Redox Reduction. That all said, please read the rest of the article before I over sell any one on a UV Sterilizer or Mineral Blocks (such as Wonder Shells). As often good aquatic husbandry is all that is necessary for a good Redox Reducing environment. 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 though. NATURAL REDOX Including Human Studies:  Over geologic time abiogenic (not biological in origin), biogenic (produced by living organisms) and anthropogenic (processes are those that are derived from human activities, as opposed to effects or processes that occur in the natural environment without human influences) deposits were accumulated in rivers, lakes and seas. Simultaneously there proceeded the self-purification of natural water on the basis of the chemical reactions of oxidation and reduction. Living organisms such as fish are adapted not to "perfectly clean water", such as distillated water, but to ecologically clean water with definite content of organic and inorganic compounds, micro-admixtures, ions and even bacteria or saprophyte (any plant that depends on dead plant or animal tissue for a source of nutrition and metabolic energy, e.g., 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 cycle toxic hydrophobic organic compounds (molecules that are repelled from a mass of water) are oxidized to the hydrophilic forms (a molecule or portion of a molecule is one 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), which are characterized by the better biological compatibility. Energy of oxidation of degrading organic compounds is absorbed during reduction chemical transformations. Excess of ions of the heavy elements transforms into insoluble, inert, nontoxic forms. Concentration of ions of light elements is stabilized. Just in such water live the water organisms, and land animals drink such water. 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 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). ORP can change so rapidly, however in a stable condition of electrons, 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 case of dilution of polyvitamin preparations in electrochemically purified water ORP of mixtures is decreased approximately by 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." Source: http://www.ionizers.org/water.html A further point from human studies shows this: “Dr. Uchiyama working at a general hospital in Japan conducted a complete medical checkup with his 871 clients, with the result of 92 of normal result (judged healthy) and 279 of requiring further consultation or treatment for their health (judged potentially sick). He measured OPR of all of their urine. Interesting result was found that many of 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.”  REDOX POTENTIAL (BALANCE) AS IT PERTAINS TO AQUARIUMS: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 reduction, these elements need to be replaced. Important; what is often missed (including by myself in earlier research), is that although you may test and for instance find high calcium levels in an aquarium via a GH over 300, that 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 state of balance in aquarium Redox. This again is where many (again I have to admit that I have been guilty of this too) will claim that their calcium or other minerals or high enough or even too high (as many still get 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; (1) 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 as well by the fact that this process is taking place. 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! (2) As to 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, Bio Home 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. All this said as to Reduction, generally de-nitrification processes CANNOT keep up with oxidation processes 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 Bio Home can also indirectly affect Redox. Important! 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. 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. 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 he 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 many aquatic forums. The more I have studied and observed in this subject, the more I feel it should not be ignored. 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 uninformed aquarists against UVs, too high a GH (which is not always a good indicator of electrolyte balance anyway), and even Wonder Shells is ludicrous. Your GH may test higher than desired but in actuality is maintaining a healthy Reducing Redox via Calcium (Facts about Calcium, an essential reducer), Magnesium, etc. REDOX BALANCE 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. 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 forums. Healthy Redox Potential (Balance) maintenance methods:  [1] 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 Redox is another reason for water changes and is also a major reason to not use drinking water 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 the Aquarium Cleaning Machine) that can drain and then continue to remove mulm that is easily emptied from the micron filter. Also ponds with “flow through” or spring fed water sources will maintain a good Redox Potential by virtue of the constant addition of fresh, lean and mineralized water, which is why many lakes will become less “healthy” during the late summer months when stream that feed them “dry up”. [2] Good aquarium circulation [3] 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! [4] Proper Calcium, Magnesium, sodium, and general electrolyte levels, THIS IS VERY IMPORTANT! AS noted earlier, this is an on-going process and although I stress to maintain a GH of over 100- 200 or even higher, this is also 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 electron and is not aiding in your Redox balance which is why using miner blacks or similar concepts is so important (Wonder Shells help here). 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 he whole picture (such as an ammonia test kit measuring ammonia which is 'bad' or ammonium which is 'not nearly as bad' if this comparison makes since). I have a good article dealing with kH, Calcium, and Magnesium here: CALCIUM, KH, AND MAGNESIUM IN AQUARIUMS; How to maintain a Proper KH, why is calcium important [5] The a UV Sterilizer is one more predictable and proven tool here (when properly installed), but also not a cure all to otherwise poor conditions. UVs work two ways in my research; [1] they morph oxygen (O2) molecules into Ozone (O3), the O3 quickly degrades, the UV then [2] 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 radiation), you break down radicals such as Ozone in your aquarium. As noted earlier in this article, please reference this article for more about this important subject: “Aquatic UV Sterilization” [6] 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). Poor lighting is not an “only” cause, otherwise my example in reason one about the lakes in late summer would not be possible (although even in these lakes, there is often poor light penetration due to murky poorly circulated water, so light is still a factor here as well to a mild degree). In Reef tanks using Metal Halide lighting, poor Redox is almost never observed and the same can be stated, albeit to a lesser degree (as this assumes good mineralization and other factors) with freshwater aquariums using lighting with good output of photosynthetic active radiation (PAR). The reasons are admittedly not completely clear as of writing this article update, however from my observations and tests, I believe correct lighting plays a role similar to UV Sterilization as explained above, especially (in the case of freshwater where poor lighting is often more common) when lighting with poor PAR qualities which are generally found in lights with approx. 6400 Kelvin temperatures. My suspicions are that although PAR has been scientifically established to be important for plants, it may also play and important role for fish as well (similar to how humans derive the benefit of vitamin D production from sunlight) For Redox problems, possible problems : * 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 our 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. Check your cleaning procedures. 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 Reducing Redox environment in. * A lack of electrolytes, as mentioned earlier, Wonder Shells 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. *As noted earlier, good lighting and the addition of UV Sterilizers can play an important role for a balanced aquatic Redox Potential A simple test of Redox can be performed using Methylene Blue and any reducer such as powdered Wonder Shell. Simply add about ½ teaspoon powdered Wonder Shell to 8 oz. of water, stir, then add one drop of Methylene Blue to the solution and stir. The Methylene Blue will dissipate due to the reducer. Taking this test a step further into the real world, if you add Methylene Blue according to standard dosage to your aquarium water (remove the water for this test), and it stays a brilliant blue, you probably have a positive Redox. If the color dissipates at all (even the slightest) you probably have a reducing number. This test in no way replaces the accuracy of Redox meter, but it is a simple way to get a handle on your aquariums Redox health. SUMMARY: This is a relatively unexplored are 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 positive Redox was good), 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. However, there is a lot of research of both my own and outside the aquatic community (which unfortunately still passes around anecdotal information as to keeping only a positive Redox) that supports these conclusions. 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 article sited were all more than 15 years old which may explain much of the out of date information). Although admittedly still a hypothesis more and more well funded research (mostly outside the aquarium industry/hobby where few of these aquatics writers seem to dare venture) point to the importance of Redox reduction as well!! 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. I really is not that hard 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. Sadly many Aquarium Wiki articles I have read are guilty of this such as the Redox article itself! 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, knowing that Redox naturally will often balance itself, you must realize that these electrons necessary for balancing Redox are often used up and the assumptions often made about GH, UV Sterilization simply do not fit the evidence! On the other side, the more complex equations of Redox are certainly worth learning (I am still trying to “grasp” them all, I would not let it frustrate you if they are hard to understand. Simply put four areas of aquarium or pond keeping have a noticeable effect on a healthy reducing Redox (as well a fifth albeit temporary aspect): (A) Regular and effective water changes (B) Proper ONGOING mineralization, especially of calcium and magnesium. (C) UV Sterilization (D) Good de-nitrification, plant filtration. (E) Keeping the production of nitric acid to a minimum and balancing this out with adequate KH levels. This also (as well as water changes) lowers DOC which lead to poor Redox levels (F) Use of water conditioners (for use in chlorine/chloramine removal) such as 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 do to their strong reducing abilities, however this cloudiness is short lived in healthy aquariums. For more about aquarium water conditioners, please read this article: “Aquarium Water Conditioners”. For further information about WHY YOU SHOULD USE A UV STERILIZER Credit for some of this information: www.redoxdrink.com/redox_potential_info.htm Another good article about this subject that I found is this: ORP and the Reef Aquarium 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. More Resources/references: Redox and Electrochemistry Oxidative stress as an initiator of cytokine release and cell damage http://circ.ahajournals.org/cgi/content/full/114/14/1531 http://www.water-prox.com/mineral_redox_right.htm http://www.unl.edu/RedoxBiologyCenter/seminars_minisymposium.shtml http://amasci.com/amateur/elecdir.html For more aquarium information and articles (pond too), please visit this site:   
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