Reef Calcium, 100 mL / 3.4 fl. oz. Maintains calcium and accelerates coral growth A concentrated bioavailable polygluconate complexed calcium intended to maintain calcium in the reef aquarium without altering pH Polygluconate complexation confers several benefits; increases calcium bioavailability, and provides a rich source of metabolic energy for peak growth Polygluconate complexation also prevents precipitation and alkalinity depletion, and contains no nitrogen or phosphate 250 milliliters treats 1000 US gallons