Importance of Testing Water Parameters

by Aquatics on May 27, 2010

Written by Chris C. who works in Drs. Foster and Smith’s Technical Support Department.


Whether you own a pond or a freshwater aquarium, testing the water is extremely important. When water parameters are not within normal range, this can cause severe stress to fish. This stress can lead to disease and sometimes loss of the animal.

The main parameters to test for are pH, ammonia, nitrite and nitrate. If you are adding aquarium salt to your pond or aquarium, you will want to test salinity levels as well.

A pH of 7 is considered neutral, anything below is acidic or anything above is alkaline. When the pH reads slightly lower or higher, this can be stressful on the fish. It is not recommended that you raise or lower pH more than 0.3 units in a 24 hour period as doing so too quickly has more of an effect on the fish than we realize. For example, pH of 5.5 is 10 times more acidic than a pH of 6.5. Even though this appears minimal to a human, this can cause quite a shock to a fish. The correct pH should be within a range of 6.0 to 7.5 for freshwater aquariums. African cichlid aquariums require a pH from 7.8 to 8.5 and brackish aquariums should have a pH from 7.5 to 8.4.

Ammonia and nitrites are very toxic to fish and should read zero ppms (parts per million) at all times. Nitrates are not as toxic, 50 ppm is an acceptable level for ponds, freshwater community, African cichlid and brackish aquariums and 30 ppm is an acceptable level for planted and discus aquariums. However, the ideal level is as close to zero as possible. These levels can normally be maintained by performing weekly water changes of 10% or biweekly water changes of 20%. Test the water at least once a week in established aquariums or ponds to ensure they remain stable.


We suggest testing aquarium and pond water with liquid test kits due to the fact that they are much more accurate than your standard “dip strip” test kits. When testing, be sure to hold the bottle of testing solution straight up and down as holding it at an angle can prevent you from getting a true reading. We recommend the PondCare Pond Master Liquid Test Kit and the Aquarium Pharmaceuticals Freshwater Master Test Kit.

Various monitors can also be used to ensure water parameters are correct, such as a pH monitor, salinity monitor or refractometer. We prefer the Vital Sine pH & Temp Gauge and/or the Vital Sine refractometer. These products will provide you with accurate readings of the pH, temperature and salinity levels of an aquarium when properly calibrated. You should always follow the manufacturer’s instructions.

Caring for a pond or aquarium can be easy as well as enjoyable provided stable water conditions are maintained. This can be achieved using proper, accurate testing equipment and a little tender loving care so your fish can live long and healthy lives.

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isaac May 28, 2010 at 1:52 am

What are the possible impurities in tap water in the US? And what kind of test kits would I need?

Shannon May 28, 2010 at 8:11 pm

Thank you for a great post. I prefer using the liquid kits too even though the dip strip is quicker but the quality of the water is so important. I love our aquarium and spending time taking care of the water, fish and overall tank.

Chris C. June 2, 2010 at 2:24 pm

Thank you for your question. Tap water can have chlorine, chloramines, ammonia, nitrate, phosphate and heavy metals. Some can be very toxic to fish, while others are troublesome for an aquarium. Each areas water source is different and we recommend contacting your local water supply company. They should be able to provide you with a copy of recent test results. You may also purchase a TDS (total dissolved solids) meter.

If well water is used as the source water, the up side is that it does not contain chlorine or chloramines however, it is generally much harder than tap water. To find out, you can test the water at home using a pH test kit or send samples to a water company for analysis. Testing companies can be located by doing a search online and may cost up to $100.00.

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