Sera Calcium Test Kit
This test monitors the calcium level easily and precisely in steps of 20 mg/l (ppm).
Calcium requirements tend to increase in most reef aquariums as they grow and mature. As a result, your old supplementation regimen may no longer be adequate. If regular testing is not performed to monitor calcium levels, it is very easy to allow levels to drop precipitously. In reef aquariums heavily stocked with corals and invertebrates, it is crucial that calcium levels be assessed every two weeks; or even better, once a week. Alkalinity should also be measured and monitored since there is relationship between calcium and alkalinity levels
If calcium levels get too high (over 500), there is a tendency for alkalinity to drop, affecting the buffering capacity of your aquarium water. Without adequate buffering, pH levels become susceptible to fluctuations. Conversely, if alkalinity gets too high, calcium levels will tend to fall as calcium precipitates out of solution in the form of insoluble calcium carbonate, also causing pH fluctuations. Ideally, calcium levels should be between 400 and 450 ppm, while the alkalinity should be between 2.5-3.5 meq/L (7-10 dKH).
It is important to monitor calcium and alkalinity levels weekly and supplement accordingly to keep them at proper levels. Low calcium levels negatively affect the growth, health and coloration of corals and what little growth that may occur result in thin, spindly branches lacking vivid coloration.