ASF Calcium Booster powder is an essential macro elements for the formation of Aragonite, a carbonate mineral necessary for the building blocks of both SPS and LPS corals. ASF Calcium Booster is an optimal blend of calcium and strontium designed to restore and maintain calcium to levels found in natural seawater. It allows easy adjustment of the calcium content and improves the growth of corals and invertebrates. The optimal calcium level is between 400-450 ppm and the optimal strontium level is between 5-15 ppm.