What is Calcium?

Calcium is an element which corals use with carbonate ions to build skeleton when they grow. 

It depletes over time as things with a skeleton (like corals and invertebrates) use it with carbonate ions to build their skeletons as they grow.

How to dose calcium

If your Ca is lower than 420, you need to dose some calcium solution to bring it back into range. You can’t raise calcium back to its original value through water changes alone. 

Dosing calcium follows the same rules as dosing KH, 

Begin by adding a buffer every day - we can help you decide on the daily dose. It is very important that Ca stays as stable as possible, so a dosing pump will help with this. Make sure calcium is added to the tank at least 15 minutes after any KH.

If the Ca is falling, up your daily dose. If it is rising, then lower the daily dose. It's best to have calcium going in many times per day using a dosing pump.