Testing water parameters weekly helps prevent invisible water problems that can be harmful to fish. Fish continually release ammonia into the aquarium through their gills, urine and solid waste. Uneaten food and decaying organic matter also add ammonia to the water. Small amounts of ammonia stress fish; large amounts of ammonia kill fish. Ammonia is the #1 killer of freshwater fish. The Ammonia Test Kit for freshwater and saltwater squariums contains two liquid dropper bottles, easy-to-read instructions with information on how to test and correct unsafe water conditions, two color charts and glass test tube with snap-tight cap. This test kit reads ammonia levels from 0 to 8 ppm. Use the Ammonia Test Kit several times a week for 4-6 weeks when you start a new aquarium, and then use it weekly for monitoring or when problems occur. This aquarium test kit is for use in freshwater and saltwater aquariums.