API pH Test Kit API pH Test Kit monitors pH to maintain healthy freshwater conditions. It is fast, easy, and accurate reading for pH 6.0-7.6 pH is the measure of acidity of water. A pH reading of 7.0 is neutral. A pH higher than 7.0 is alkaline, and a pH lower than 7.0 is acidic. Maintaining the aquarium at the proper pH ensures optimal water quality. The pH should be tested weekly, since natural materials in the aquarium (such as fish waste and uneaten food) can cause pH shifts. Taking a few minutes each week to maintain and monitor aquarium conditions is the key to a healthy aquarium. pH control is imperative to prevent the harmful effects of overly alkaline or acidic aquarium water on fish and plant life. Fish require a specific pH level to thrive. However, pH in an aquarium can fluctuate due to fish waste, addition of tap water and the build-up of natural acids. Use this kit to easily and accurately measure the pH level and maintain a healthy freshwater community aquarium. For use in freshwater aquariums.