NSW contains 400 - 450 mg/L calcium Which is also the value we should strive for.

Calcium is a major constituent of calcareous algae, the skeletal material of hard corals and the skeletal needles of soft corals. Calcium also fulfils many biological functions.

In a healthy aquarium the growth of these and other organisms results in calcium depletion.

Without a sufficient amount of dissolved calcium in the water, many reef organisms will not grow and develop properly.

Fluctuation in calcium levels should be avoided.