Magnesium plays a critical role in marine aquariums by maintaining a balance between calcium and alkalinity. It is impossible to maintain calcium and alkalinity at the proper levels without also maintaining magnesium. A proper magnesium level is also critical for the health and vitality of many reef aquarium inhabitants. The biologically useful forms of magnesium used in FRITZ RPM MAGNESIUM are utilized in the growth and development of many corals, invertebrates and beneficial calcareous algae. FRITZ RPM MAGNESIUM is formulated using only the highest purity magnesium chloride and magnesium sulfate in a balanced ratio, helping the aquarist to maintain the correct ratio of chloride to sulfate ions found in natural seawater.