Procedure for Fish Water Testing

One of the best ways to keep your fish healthy is to test the water they live in. Chemicals caused by the decomposition of waste in the tank can build up in a surprisingly short time in a closed system like a fish pond or fish tank and become toxic to your fish. Even new water should be tested and treated before you put your fish in it.

  1. What to Test For

    • It's important that you not only know how to test, but that you know what you are testing for and why. Buy a good test kit and you can test for chlorine, ammonia, nitrites and nitrates, pH and water hardness. Every test kit is different, but they all come with written instructions for how to perform the tests. If you don't have the instructions, don't use the kit.

    Chlorine

    • Chlorine kills not only germs, but also your fish. When adding new water to a tank, you need to check your chlorine level with a chlorine test kit. Chlorine neutralizers usually come with the test kit. Add the neutralizers according to directions until the water tests clear of chlorine.

    Ammonia

    • Next, test for ammonia. Ammonia is the direct result of fish peeing in the water. Ammonia levels inevitably rise if you have fish in the tank. Some filters and additives reduce ammonia, but for the most part a periodic 25 percent water change should keep ammonia levels under control. If you get a sudden high ammonia level, treat it immediately or remove the fish and change the water. Ammonia levels should always be kept below 0.1 parts per million (ppm).

    Nitrites

    • Test for nitrites, a chemical created by bacteria eating fish wastes. Nitrites are poisonous to your fish if the level of nitrite rises much above 0.3 ppm. Regular partial water changes are the best for controlling nitrites.

    Nitrates

    • Nitrates are a result of the conversion process of ammonia and nitrite. While not as toxic as either, they should not be allowed to build up. Professional aquarium keepers recommend that you change a fourth of the water in your tank every week. This can be done when you suction waste from the gravel and helps prevent the water from becoming cloudy.

    Testing pH

    • Some fish have no problem with the pH balance of the water, but many tropical varieties do. It is easy to test. Between a measured pH of 6 and 8 is where most fish are comfortable, but a pH of 7 is neutral and safest. Above 8, the water is too alkaline. Below 6, the water is too acidic. Chemicals to correct pH can be purchased at a fish store, but follow label directions very carefully. Though different fish like different pH levels, all fish react badly to sudden drastic pH changes. Try not to change the pH more than a point or two in 24 hours.

    Water Hardness

    • Water hardness testing is not especially critical, but should be done on occasion to prevent a shift in water quality over time. Hard water tends to be alkaline and soft water to be acidic. When adding tap water to your aquarium, test the pH first and adjust it to match the water in your tank. This avoids a sudden jump or drop in pH that might be bad for fish or plants.