Water Testing For Your Pond
Reprinted from The Valley of the Sun Koi Club Newsletter
Tests! "We don't need tests!" the cry of the beleaguered pond owner who has problems enough dealing with algae, malfunctioning filters and pumps, pond leaks and sooner or later sick fish. Monitoring water quality in a koi pond is often viewed with the same degree of enthusiasm as preparing a tax return. Who subjects oneself to another bunch of problems? Well, if your tax return is not prepared, your tax problems will not just go away, and if you don't test your pond water, your water quality problems will not just go away.
Unlike paying taxes, testing our ponds is entirely voluntary, so let's consider three good reasons for volunteering. First, knowledge is power. Second, prevention is easier than cure. Third, learning can be fun. The reasons for not testing - to time consuming, too confusing, too expensive and just not necessary - don't stand up in light of the facts, as we shall see. Another consideration is that we generally have koi ponds for two basic reasons - the beauty of the water environment and the pleasure of having koi. Water testing goes to the heart of both these issues - keeping the pond attractive for our enjoyment and keeping the water healthy for the fish. The latter is the most important reason to test. As hardy as koi are, long term exposure to poor water quality will cause stress and disease. Unfortunately, we can not rely on our unaided senses to determine water quality - clear water is not an indication of good water quality from a fish's perspective.
Millions of years of evolution have resulted in fish that are superbly adapted to their environment. An attempt to create and maintain an artificial pond environment for even domesticated fish is complicated by the fact that fish are essentially "bags of water living in water" with only a semipermiable membrane to maintain internal integrity.
Terrestrial animals, as ourselves, can be considered "bags of water living in air" with enhanced barriers that, relative to fish, effectively separate and protect us from our environment. We can tolerate pollution and environmental changes much better than fish can because our bodies do not interact with the environment as intimately as do fish bodies. Fish are truly a part of their environment and are strongly and directly affected by its condition.
Because koi are so adapted to and affected by their environment, it is important that natural, healthy conditions be maintained in a pond to ensure healthy, happy, colorful fish. Fish disease issues invariably involve water quality. Poor quality stresses the fish, which in turn causes their immune system to go down, which in turn makes the fish susceptible to disease pathogens. In order to know if there is good water quality, it only makes sense to test it periodically rather than wait for disease symptoms to appear.
"A pond is basically a toilet". Fish waste must not be allowed to accumulate in a pond, which usually means a biological filter must be operating properly. Fish waste and other organic debris are the first step of the nitrogen cycle, a series of events that produces some of the compounds we test for - ammonia, nitrite and nitrate. Algae may colonize and detoxify a pond with high levels of nitrogen compounds, but alga's presence changes water quality for two other things we should test for - pH and dissolved oxygen. The last naturally occurring factors we routinely check are temperature and water hardness. When to Test
Individual, one-time tests are only important if the test results indicate a toxic or dangerous condition, such as high ammonia, where corrective action has to be taken immediately. The greatest benefit of testing, however, is obtained when results are plotted on graph paper over a period of several testings, so that trends or directions can be noted early. By knowing the direction your pond's water quality is taking, you can take corrective action before the problem gets out of hand.
Normally, tests for ammonia, nitrite, nitrate, pH and temperature should be made once every week or two. Tests should be made more frequently during periods of change in the pond, such as spring warming, new filter installation, major pond cleaning or repair. At such times daily testings for certain items may be necessary, for example pH test during cement work and ammonia and nitrite tests for new filters. During stable periods such as mild summers, testing may be cut back to once every three weeks, and during periods of midwinter inactivity, testing can be eliminated. Test Kits
Home kits all work the same way - there is a small container for a measured sample of pond water, a chemical to add to the sample that will cause the water to turn a certain color, a color chart to compare the result to and instructions to tell you if things are OK or not. Some kits use drops and some use tablets - drops are faster but tablets are easier to measure. Test kits come in either "Master Packs" which contain several basic tests or a single test pack. Refills are usually available and most of the chemicals have expiration dates after which they don't work properly. The basic tests are usually ammonia, nitrite, nitrate and pH.
The following is a discussion on the specific factors tested in a Koi pond. You do not need this information in order to properly test your pond, as the commercial test kits are simple and easy to understand. Read this only if you care to understand the factors behind the test results. Don't worry about the technical measurements, because the color charts in the test kits really make things very simple. There's no reason to convert mg/liter to oz/gallon because only the ratio matters and you don't even need that to read the color chart. What is important to realize, however, is the interrelationship between pH and various factors in the pond. Also, results may vary depending on the time of day and how long the water sample was stored before being tested. Ammonia
is introduced by the fish waste and decomposing organic debris, is the most toxic nitrogen compound. It is present in two forms in the pond - free and ionized. Free ammonia is the most toxic and will cause death in very low concentrations. Problems associated with non-lethal elevated levels of ammonia include gill disease, dropsy and finrot. The higher the pH and the temperature, and the lower the salinity or hardness, the greater the ratio of free ammonia to the ionized form. Thus, the higher the pH and or the temperature, the more toxic the ammonia. Test kits measure the total ammonia (free plus ionized). With a properly functioning biological filter, the ammonia level is usually zero in the pond and should be under .1ppm (mg/l). Nitrosomonas bacteria in the filter oxidize ammonia into nitrite, our next compound. If the level of ammonia is elevated, you should immediately add ammonia remover such as Tetra Aquasafe, Kordon AmQuel or make partial water changes. You should also add nitrifying bacteria to your filter and stop feeding your fish until the situation is corrected. Nitrite
is less toxic than ammonia, but still very toxic as it inhibits the ability of the blood to carry oxygen. Nitrite is oxidized into nitrate by Nirtrobacter bacteria living in the filter, but some of the commercially prepared bacteria compounds for ponds are rather skimpy in the amount of Nitrobacter present because it is relatively expensive. Thus your pond may experience a nitrite spike as your filter is being conditioned until the Nitrobacter colony reaches sufficient size to deal with all the nitrite. If the nitrite level is elevated according to your test results, you should make a partial water change and add bacteria high in Nitrobacter, such as Aqua 5 Nitrate
is the end product of the nitrifying phase of the nitrogen cycle. It is much less toxic for koi than either ammonia or nitrite. It is however, a nitrogen compound that is the food and the fertilizer for algae. In nature, nitrate is absorbed by water plants and is reduced into free nitrogen by anaerobic bacteria living in the bottom silt. Hydrogen sulfide and methane gas are given off as a by-product of the anaerobic filtration. An oxygenated, clean pond will not have any anaerobic bacteria present, so nitrate will accumulate in the pond. An algaecide is often used to control algae that would be attracted to the nitrate. Partial water changes of 1\10th per week will flush out the accumulating nitrate. If the nitrate level is over 20 mg\l, you should make water changes immediately or add Aqua 5 Dry, which contains bacteria that remove nitrate without producing hydrogen sulfide and methane gas. pH
indicates the ratio of hydrogen ions to hydroxyl ions on a logarithmic scale from 0 (pure acid) to 14 (pure alkaline). Pure water is 7.0, meaning that there is an equal balance of hydrogen ions and hydroxyl ions. Most tap water in the southwest is between 7.4 and 7.6, which is perfect for koi, as they do best in water 7.2 to 8.0. Koi can actually tolerate a wide range of pH, from 6.5 to 9.0. but they cannot tolerate a rapid change - more than .2 per hour. (Note the logarithmic scale means that there are 10 times as many hydroxyl ions at 8.0 as at 7.0). As mentioned above, pH affects the free ammonia\ionized ammonia ratio, with a higher pH resulting in a greater concentration of the more toxic free ammonia. To make things more complicated, algae and other water plants can drastically change a pond's pH from night to day, due to a change in the amount of dissolved carbon dioxide present in the water. We're concerned about rapid pH shifts not only because of the ammonia ratio, but also because the fish are trying to keep their blood pH even during these shifts, thereby causing stress. Carbon dioxide mixes with water to form mild carbonic acid; therefore, more carbon dioxide means a lower pH, and less carbon dioxide means a higher pH. A bloom of algae will take up a lot of carbon dioxide during daylight for photosynthesis and emit a lot of carbon dioxide at night during respiration. Buffers such as bicarbonate ions help maintain the amount of carbon dioxide and therefore the pH remains even in the pond, but if there's too much algae for the available carbon dioxide, it will be obtained from the bicarbonate ions in the water, thus reducing the buffering agent and increasing the risk of rapid pH changes. Finally, even though koi can tolerate extremes of pH there are diseases directly caused by the stress. Acidosis is a reaction of fish to acidic conditions, in which they act highly agitated, with a lot of jumping. A rapid lowering of pH will cause quick death, while a slow lowering below tolerance levels will cause few behavioral changes until the inevitable death. In alkalosis, a reaction to conditions that are too alkaline, the gills and fins are destroyed; otherwise the symptoms are similar to acidosis. Continued high pH can be caused by improperly cured or sealed concrete ponds or mortar work. New concrete ponds should be sealed with penetrating water based or epoxy compounds, which not only provide a water seal, but also bond with the lime to eliminate pH problems. Cement based water seals don't do anything to control pH. For temporarily raising or lowering pH, you should use sodium bicarbonate or sodium monophosphate respectively. If fish are in the pond be sure to alter pH gradually - no more than a 0.2 change per hour. If an algae bloom is causing the pH shifts or extremes, you have to first determine if you filter is working properly, in which case it's safe to kill the algae (while monitoring dissolved oxygen levels). If an improperly operating filter is the cause of the algae bloom, you have to first ensue safe levels of ammonia and nitrite before it is safe to control the algae. Remember, go slow in fixing the problem that probably took a long time to develop. Finally, if algae are present, take an early morning and a late afternoon reading before taking corrective action. Temperature
is often viewed by pond owners as a guide to feeding, more than as a health issue for koi. Temperature should be monitored for both daily and seasonal extremes. Temperature affects dissolved oxygen levels, respiration, metabolic rate, pH balance, free ammonia\ionized ammonia ratio and osmoregulation. Koi can tolerate a broad range of temperatures, from ponds that are iced over; to water up to 90F, better than they can tolerate sudden shifts in temperature. If you have a shallow pond (less than 2 feet) in full sun along with cool summer nights, the pond temperature may be changing by more than four degrees an hour, causing stress to the fish. Greater splashing of the water and shading may control the problem. If your pond is subject to stressful temperature changes, a 0.1% solution of sea salt containing calcium, potassium, sodium and trace elements will reduce the stress as it aids the kois' osmoregulation. As with pH, do not drastically alter a pond's temperature . Fish can tolerate a low to a high temperature change better than a high to low change. Water Hardness
consists of two elements, permanent or general hardness and temporary or carbonate/bicarbonate hardness. Koi do better in hard water because of the relation of salt within their bodies to the dissolved salts in the pond. In soft water, the difference in salt concentrations means the koi have to work harder, through the process of osmoregulation, to prevent the salts within their bodies from diffusing out through their gill membranes. Harder water allows the koi to ease up on osmoregulation and therefore reduce stress. As mentioned above, bicarbonate ions buffer the water, reducing pH shifts, another cause of stress in koi. Koi do well in carbonate hardness of 150-300 mg/liter or 9-18 degrees dll. In most koi ponds the water is too soft due to the fact that there is no natural mud bottom that leaches minerals into the water. Marine salt and sodium bicarbonate increases hardness and will also cause pH to go up. A permanent salt solution of 0.1% is beneficial to koi, and works out to eight pounds per 1,000 gallons. Check your pH if you add salt, and do not use table salt. Salt will not evaporate out and needs to be replaced only if water is drained from the pond. Dissolved oxygen
is usually only a warm weather concern, as it is associated with water temperature and algae. However, the larger the fish, the greater the oxygen demand - low levels will stress and kill your biggest koi. Ponds that have been safe for many years become unsafe as your fish grow larger. The colder the water, the greater its capacity to hold dissolved oxygen. Algae takes up oxygen at night, and an algae bloom can cause suffocation in large fish and inhibit the oxidation process of nitrifying bacteria. Also, dying algae and decaying organic material takes up oxygen. Testing for dissolved oxygen allows you to determine if your pond has the maximum amount of oxygen for the temperature of the water. Splashing the water into small droplets with a fountain or waterfall is best for aeration, although venturi valves on underwater jets and air compressors also do a good job of oxygenation. Chlorine and Chloramine
should be tested for if your water supply is from any source other than your own well. Chlorine will burn off by itself in a day or so, but chloramine must be broken down and removed chemically. Check with your local water agency to determine whether they add chlorine or chloramine. These chemicals damage the gills and liver and even in low concentrations can cause stress that ultimately leads to disease. Also, frequently overlooked is the fact that they are added to the water supply to kill bacteria. The beneficial, nitrifying bacteria in you biological filter can be killed off by chlorine and chloramine in concentrations that do no obvious damage to your fish. Good products on the market to eliminate chlorine and chloramine include Tetra Aquasafe, Kordon AmQuel and Aqua 5 chlora Gone. Copper
should be tested for if water supplied to the pond is via copper pipes or if coins are thrown in the pond. Copper, in its toxic form will leach into soft water more readily than into hard water. It damages skin and gills and can cause sudden death that is very hard to trace. It also kills the nitrifying bacteria in your filter, which results in an ongoing algae problem. Copper is used in several pond treatments and should be monitored if you are using any such treatments. Concentrations above 0.015 mg/liter are dangerous to fish, and even lower levels can kill the beneficial bacteria in a biological filter.
In conclusion, testing gives you the information you need to ensure the best possible conditions for your fish, as well as the information needed to maintain water clarity. It only takes a few minutes a week, and is about the best investment of pond maintenance time you can make.