Specially formulated mixture of dissolvable solids (also called general hardness or GH) which includes major salts of sodium magnesium calcium and potassium together with all necessary minor and trace minerals together with a small amount of carbonate alkalinity (KH) to reproduce artificial river water (most aquarium fish are river fish). Provides natural water chemistry for the conversion of reverse osmosis distilled or deionized water for fresh water fish and plants. Provides a balanced electrolyte system. Useful for all fresh water fish including Discus. This is the premium dry formula used the world over to raise discus and other freshwater species. Contains no phosphates nitrates silicates or organic chemicals to pollute the system! R/O RIGHT is unmatched for quality and value!