Reef Calciumª is a concentrated (50,000 mg/L) bioavailable polygluconate complexed calcium intended to maintain calcium in the reef aquarium without altering pH. Polygluconate complexation confers several benefits: it increases the bioavailability of the calcium, it provides a rich source of metabolic energy to help maintain peak coral growth, and it prevents calcium precipitation/alkalinity depletion. Polygluconate contains no nitrogen or phosphorous, thus it is biologically impossible for it to lead to algae growth in a properly maintained reef system. Guaranteed Analysis (Amounts per 1 g): Calcium (min)ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ 50 mg, Calcium (max)ÉÉÉÉÉÉÉÉÉÉÉÉÉÉÉ 52 mg, Ingredients: calcium gluconate. 500 ml treats 2115 gallons