For optimum results the Calcium levels in marine tanks need to be checked regularly to determine the uptake in your system. Simply calculate dosing requirements to suit the depletion rate using the easy to use dosing calculator on www.coralessentials.com. After you have determined this, a regular check of the calcium levels should be made. Your tank will change over time as coral grows, new pieces are added. We have found ideal calcium levels to be at about natural sea water levels for most aquariums. Levels of 430-470ppm are desirable if you want to maintain high levels of growth in a SPS and hard coral dominant system.