Description : 2231439941_6416928517 Reef Advantage Calcium is a non-caustic (pH 8.3-8.6) optimized blend of ionic calcium designed to restore and maintain calcium to levels found in natural seawater. Calcium and carbonates are essential to all coral growth. If either becomes deficient; coral growth will cease; followed by a rapid decline in coral health. To prevent this you must provide calcium (Reef Advantage Calcium) and carbonates (Reef Builder or Reef Carbonate). Reef Advantage Calcium also includes magnesium and strontium in amounts proportionate to typical utilization ratios. 1 kg treats 8000 gallons.