Why put lime in your ATO?
It's called 'dripping kalk', from the German word for lime. It's appropriate for anyone with clams or stony coral, ie, a tank that sucks up calcium faster than weekly water changes can supply it.
This is why stony coral keeping is a lot easier than people think it is---easy, as in, "very little work"...as in, "actually far less work than keeping a FOWLR."
First you need an ATO [automatic topoff]. Everyone does who...