Fluval Sea CalciumOur Fluval Sea Calcium is a concentrated form of calcium that's easily absorbed by corals and other invertebrates. It helps develop a strong skeletal structure, while not affecting the delicate ionic balance in Marine aquariums. Fluval Sea Calcium contains USP (Pharmaceutical) Grade calcium chloride, which ensures that you're getting a high quality and ultra pure product that's free of unwanted contaminates. It does not contain gluconates, nitrates or phosphates. Fluval Sea is strongly recommended to offset the constant depletion of calcium by coral, coralline algae and other invertebrate growth.