The pH value of water is a measure of the degree of acidity or basicity, with values ranging from 1 (acidic) through 7 (neutral) to 14 (basic). It is important to monitor the pH of your aquarium water because all forms of life, from fish and plants to algae and filter bacteria can show adverse reactions if kept outside their preferred pH range, or if subject to sudden changes in the pH value. In natural marine conditions the buffering action of bicarbonates and carbonates maintains the pH at a very constant value of 8.2-8.4. This value should be replicated in your marine aquarium. The Tetratest® pH kit was professionally developed to accurately determine the pH level in your aquarium water. To ensure optimum water quality, frequent testing is recommended. The kit contains on 10-ml test reagent, test vial, color scale, instructions and recommendations and 50 tests.