The API 5-in-1 Test Strips are ideal for both fresh and saltwater aquariums. This is a quick and easy method of testing for pH, nitrate, nitrite, general hardness and carbonate hardness. There is no separate vial needed for testing accurately. The kit comes with highly precise color charts, available in 4pk, or 25 strips and instructions on how to correct unsafe water conditions. Provides maximum accurate results for testing water quality.