[Randy Holmes-Farley]

It is just a calcium supplement. If calcium is low, you are better off adding it. If calcium is not low, you may be better off not adding it, as if it gets too high it may depress alkalinity. I'd suggest measuring calcium and alkalinity, and then deciding what to do. In practice adding a little probably won't help or hurt since to have a significant effect on calcium you typically have to add quite a bit.