Red Sea Reef Foundation B (Alk) - 500ml LiquidReef Foundation B Carbonate & buffer complex for balanced formation of Coral Skeleton Alk 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 coral health and growth. Red Seas Reef Foundation B is a complex of carbonate and other buffers present in seawater that maintain proper alkalinity and pH, and is part of Red Seas complete Reef