API General Hardness Test – Fresh ^58

Tests tap water and freshwater aquariums for general hardness(GH), the measure of dissolved calcium and magnesium ion concentrations, and(KH), the measure of dissolved carbonate and bicarbonate ion concentrations, also alkalinity. * For Fresh water * Helps detect stress on fish caused by rapid pH shifts, the result of low levels of KH * Helps aquarists duplicate the natural habitat of their fish, thereby providing a healthy aquarium environment. 2 Bottle Kit.