Fast, accurate and easy-to-use kit contains two dropper bottles, test solutions, easy-to-read instructions, color chart and glass tube with lid for 130 tests for ammonia level from 0 to 8 ppm. Why test for Ammonia Tropical fish continuously release ammonia (NH3) directly into the aquarium through their gills, urine and solid waste. Uneaten food and other decaying organic material also add ammonia to the water. A natural mechanism exists that controls ammonia in the aquarium-the "biological filter," made up of nitrifying bacteria which grow in the gravel bed. As with any natural process, however, imbalances can occur. Testing for the presence of toxic ammonia is essential, so that once detected, steps can be taken to remove it. Otherwise, ammonia in the aquarium will damage delicate gill membranes, and prevent fish from carrying on normal respiration. High levels of ammonia quickly lead to fish death. Even trace amounts can stress fish, suppressing their immune systems and thereby increasing the likelihood of disease and subsequent fish loss. Testing TipsThis kit measures ammonia levels in parts per million (ppm), and can detect concentrations of ammonia from 0 ppm to 8.0 ppm in either freshwater or saltwater aquariums. Thus, there are two ammonia test color charts, one for freshwater aquariums, and one for saltwater aquariums, so be sure to use the correct chart for your type of aquarium when interpreting test results. The freshwater ammonia test color chart is the appropriate chart to use for testing freshwater aquariums to which aquarium salt has been added.