The third component used is Preis Mineral Salt (with no sodium chloride). The Balling method is a simple and inexpensive way to ensure the appropriate supply of minerals in marine aquariums. This method has become the established way to raise calcium levels and carbonate hardness.
Preis magnesium chloride hexahydrate and Preis magnesium sulphate heptahydrate
The magnesium level in a reef aquarium should be around 1350mg/l. Use these two Balling salts to achieve the desired levels in your water.
All the salts are pure pharmaceutical grade.