Reef Foundation« A Calcium and strontium complex for balanced formation of the coral skeleton. Calcium, magnesium, strontium and carbonate are the basic foundation elements of coral skeletons. All of these elements need to be available in balanced proportions for positive coral health and growth. Red Sea's Reef Foundation A contains blended salts of calcium and strontium in the ratio required by corals and is part of Red Sea's complete Reef Care Program. Liquid supplement: 1ml will raise the Ca level of 100 liters (25 gal) by 2ppm.