Reef Fusion, 1, 4 L / 1.1 fl. gal. Raises calcium; Two part system maintains calcium and alkalinity levels Provides concentrated ionic calcium Also includes biologically appropriate levels of magnesium, strontium, boron, iron, manganese, and molybdenum When used as directed Reef Fusion 1 and Reef Fusion 2 will maintain the critical levels of calcium and alkalinity necessary for healthy coral growth 500 milliliters treats 3250 US gallons