A successful coral reef aquarium depends on how well you maintain the water parameters which are the key to a stable coral environment. All of the elements found in natural seawater play a role in providing optimal water parameters, but some are more significant than others. These elements, the foundation of the reef environment, include the three major elements: Calcium (Ca), Magnesium (Mg) and Carbonates (CO3). All three have a major effect on water chemistry (pH stability, Alkalinity, ionic strength) and on many of the coral's biological processes (skeleton formation, ions exchange, photosynthesis).The foundation elements complement each other in the formation of coral skeleton. If not balanced correctly one of the elements will quickly limit healthy coral growth.Maintaining balanced levels of the Foundation Elements (Ca, KH Mg) creates optimal water conditions for promoting strong and healthy coral growth. Reef Foundation C is a Magnesium complex for balanced formation of Coral SkeletonReef Foundation C (Mg): A blend of Magnesium salts. Concentration: 1ml will raise the Mg level of 100 liters (25gal) by 1ppm.