API pH Test Kit monitors pH to maintain healthy freshwater conditions in your tank. pH control is imperative to prevent the harmful effects of overly alkaline or acidic aquarium water on fish and plant life, so take a few minutes each week to maintain and monitor your pH conditions with this easy-to-use kit! Tests read pH from 6.0 - 7.6 and will help you quickly and easily determine whether your levels are too high or too low.