Flora Viv KH+ is a high quality product designed to raise the alkalinity (carbonate hardness (KH) or buffering capacity) of freshwater and planted aquariums at a pH of 7.8 or lower. It will increase the stability of pH over a wide range of conditions providing for safety of the entire system. It contains no phosphates, which often cause unwanted algae growth. Proper control of pH and alkalinity are among the most critical functions of maintaining an aquarium. Continuum recommends that you maintain an alkalinity level as specified in the directions.