Salifert Calcium Ca profi testCalcium 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. In a healthy aquarium, the growth and multiplication of corals, calcareous algae and other organisms can result in calcium depletion. To maintain a stable environment it