Keep your fish healthy and thriving by testing your aquarium water's pH regularly with an easy-to-use API Freshwater Aquarium pH Test Kit. Testing water parameters weekly helps prevent invisible water problems that can be harmful to fish. pH is the measure of the acidity of water, on a scale ranging from 0 to 14. A pH of 0 is the most acidic, while a pH of 14 is the most alkaline. Different geographies have different tap water conditions with different pH levels, while fish require a specific pH level to thrive.A pH of 7.0 is ideal when keeping a community aquarium containing a variety of tropical fish. Goldfish and livebearers prefer a pH of 7.5. Much Amazonian fish, like angelfish and neon tetras, prefer a pH of 6.5 to 6.8. Mollies and swordtails thrive at pH 7.2 to 7.5. API Freshwater Aquarium pH Test Kit contains 1 pH test bottle, instructions, capped glass test tube, and a color card for easy pH level testing in freshwater aquariums.API Freshwater Aquarium pH Test Kit test a wide range of pH levels from 6.0 to 9.0. Use the color-coded chart to determine if your water is safe or if adjustments are needed.