Introduction to Calcium
Calcium is a major constituent of coralline algae,
the skeletal material of hard corals and the skeletal needles
of soft/leather corals. In many cases too low a calcium concentration
retards coral and coralline algae growth. Calcium also
fulfills many important biological functions.
Calcium easily precipitates (comes out of solution) as Calcium
Carbonate, especially at higher pH values. Because of this, and
as a result of continuous usage by invertebrates, this element
is quickly used up in the limited volume of the marine aquarium.
A high Calcium level for the reef aquarium in which so many
organisms build calcareous structures is essential. A gradual
decrease in the concentration of this essential element will
result in growth stagnation and degeneration of invertebrates.
The Calcium level of natural seawater is approximately 400 ppm.
A level of at least 400 ppm should be maintained in the aquarium,
however, for optimal coral growth 450 ppm is even better.
It is recommended to measure the Calcium concentration every