Enter your aquarium water volume, current and desired calcium level, and then select your additive of choice to find out how much you need to add to reach that desired calcium level.
This calculator is designed to provide a single adjustment dose to correct fallen calcium levels. Once your desired calcium level is reached, reference the manufacturer instructions for calculating your daily dosing amount.
Keep in mind your adjustment dose will be different from your tank’s required daily dose.
If making a large adjustment (more than 50 PPM) divide the dose up and add to the tank over the course of 1-2 days to avoid dramatic changes in water chemistry.
Powdered calcium additives should be thoroughly dissolved into solution before dosing. Dose liquid solutions slowly, into an area of high water flow avoiding direct contact with pumps, heaters and other equipment to prevent precipitation. Never dose calcium and alkalinity supplements back to back, give the tank 20-30 minutes minimum in between doses.
To maintain calcium levels once the target level has been reached, it is best to dose small amounts each day, sometimes even multiple times per day. This maintains that stability in your tank and prevents rapid changes in water chemistry that will stress out tank inhabitants if you were to dose large quantities at one time.
Test and monitor your calcium levels daily until your daily dosing regime is dialed and stable. Continue with weekly testing to monitor the aquarium's progress. In aquariums with a significant population of growing stony corals, it is not uncommon to have to increase daily calcium doses every few months to maintain stable levels.