API® pH Test Kit monitors pH to maintain healthy freshwater conditions. It is fast, accurate and easy to read, working in pH ranges from 6.0-7.6. Use it during regular care, when diagnosing problems, or before using certain water treatments. pH control is imperative to prevent the harmful effects of overly alkaline or acidic water on fish and plant life. pH can naturally fluctuate do to fish waste, the addition of water and the build-up of natural acids. Use this kit to accurately measure pH levels.