Salifert Calcium Test Kit. Calcium is a major constituent of calcareous algae, skeletal material of hard corals and the skeletal needles of soft/leather corals. Calcium also fulfills many biological functions. Quite often a too low calcium concentration retards coral and calcareous algae growth. NSW contains 400 – 450 mg/L calcium. Which is also the value we should strive for. For a stable aquarium environment the fluctuation in calcium content should preferably not more than approx. 15 mg/L. This automatically means that the calcium test should be able to monitor comparable fluctuations. Our calcium test is capable in resolving the calcium content in 10 mg/L steps. The color change is sharp and facilitates the detection of small but highly significant fluctuations in the calcium concentration. Salifert is the only one in offering a true accuracy and precision as claimed. The kit can perform approx. 50 - 100 measurements.