High-end alkalinity test kit for serious aquarium hobbyists. Maintaining proper carbonate hardness and alkalinity is essential for all types of aquariums, especially marine reef aquariums. Carbonate hardness and alkalinity has an intricate relationship with pH, calcium, the buffering capacity of aquarium water, as well as healthy coral growth. The Salifert Carbonate Hardness/Alkalinity Test Kit is very sensitive and measures changes in alkalinity levels in 0.3 dKH or 0.1 meq/L increments. For marine or freshwater aquarium use. 100 - 200 tests.