Magnesium is an important element in the reef aquarium, it is essential for both the development of corals and maintaining pH. Dissolve 1g in 100ml of RODI water to make 100ml of Magnesium solution which will raise Magnesium levels by 1.2ppm in 100l of tank water. Not recommended to raise Magnesium by more than 50ppm daily. Dosing should always be monitored closely with testkits.