Water quality and testing

Water quality and testing 2019-03-17T05:53:37-05:00

Water Quality and Testing

by Phillyn17

In order keep your fish happy and healthy, you should keep their tank water clean and free from harmful bacteria and chemicals. There are many available types of equipment for testing your tank water for impurities, but for the purpose of this thread I will cover the four main water tests we should carry out, namely those to determine levels of pH, Ammonia, Nitrite, and Nitrates.


Depending on their particular species, fish need varying levels of pH, these requirements differ slightly because some fish prefer acidic, and some prefer alkaline water. You should check the pH of your tank water and try to find fish which are compatible with your water quality; a figure of between 7 and 8.5 is ideal for goldfish. Certain chemicals are available to alter pH levels. However, it’s preferred not to adjust the pH too dramatically and suddenly, as this can shock, or at worse even kill your fish.

Water quality and testing

Ammonia (NH2/NH4).
Ideally there should be 0ppm (parts per million) of Ammonia in your tank. Just the most minor trace of ammonia could be very harmful to fish. If Ammonia levels are found to be present in the water, emergency action should be taken. Perform a 50% water change immediately to reduce these levels; then continue with daily water changes of approximately 20% until the Ammonia results safely register 0ppm.

Nitrite (NO2).

As in the case of Ammonia, there should be zero Nitrite in a healthy, established and cycled tank. If you find a reading higher than 0ppm present in your water, perform an immediate 50% water change and continue with daily changes of approximately 20% until the water quality recovers and you observe Nitrite readings of 0ppm in your tests.

Nitrate (NO3).

Tank water should include Nitrate readings of 40ppm or less if your tank has completed its’ Nitrogen Cycle successfully. Such levels can be maintained by performing weekly water changes of around 25%. Readings higher than 40ppm are not recommended for long periods; you can test for any Nitrate present in your tap water, to establish if the problem lies there. If your domestic water supply has a high Nitrate reading, remember/ consider that live plants absorb Nitrates in a tank; Nitrate absorbing sponges are also available, these can be installed in your filter. But as in the case of charcoal filters that are used to reduce Ammonia levels, these are not recommended because when full they release harmful impurities back into the tank, and can dramatically spike the ecosystem.

Water test kits.

It is imperative that you obtain your own efficient, good quality water testing kit. Try and avoid relying on, and having your water quality tested by “run of the mill” pet shop assistants, who may be only too eager to assure you that your water quality is acceptable when in fact the water standard is completely unacceptable. Alternatively, they may inaccurately report that your water quality is poor when it’s not, and sell you unnecessary and expensive chemical additives to alleviate the situation. The only true method of assessing/obtaining accurate water test results is to perform the tests yourself. It’s not rocket science, and in the main just takes a few minutes to complete.

Water quality and testing

There are many types of test kits available; these include a variety of test strips and liquid test kits. Test strips are not as efficient as the liquid type kits; liquid test kits are easy to use and are more accurate than the test strip variety.

Most liquid test kits require you install a sample of your tank water in a test tube; then add the required amount of a particular chemical into the water content. You then wait for the colour of the mixed content to develop, finally referring to the supplied colour comparison chart to determine the result of that particular test. I would personally recommend the API Freshwater Master Test Kit; I find it easy to use and it supplies very accurate results.

Water quality and testing

It is very important to remember that whilst performing these liquid tests, you adhere precisely to the instructions supplied with the kit. Shake the tube as instructed for the stipulated length of time; you should also allow five minutes or so for the colour to develop as required in the tube. It can be difficult to compare the colour of the fluid in the tube with the comparisons printed on the chart, to ensure that you check the colour accurately against those on the colour chart, take your tube and chart into a room containing natural light, and the test colours will be a lot clearer.

It is highly recommended that these tests be carried out weekly; these tests coupled with the recommended routine water changes would ensure that your tank is always in a healthy condition, hopefully guaranteeing your fish a pleasant environment in which to live. Remember, pristine water conditions are paramount in a successful fish tank ecosystem.

Water quality and testing

Written by: Phillyn17

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