Seachem Reef Completeâ„¢ is a concentrated (160,000 mg/L) optimized blend of ionic calcium designed to restore and maintain calcium to levels found in natural seawater without affecting pH (formulated at pH 8.3). 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. Reef Completeâ„¢ also includes magnesium and strontium in amounts proportionate to typical utilization ratios (100:5:0.1, Ca:Mg:Sr). This allows one to maintain these two important elements while maintaining calcium. Reef Completeâ„¢ delivers 560x more calcium than is available from an equal volume of kalkwasser solution. Use Reef Completeâ„¢ to maintain adequate calcium and Reef Calciumâ„¢ to promote accelerated growth. 500 mL treats 8,000 L (2,000 gallons).