Quote Originally Posted by CarlD View Post
And the Cal-hypo adds even MORE calcium that you don't need.
Usually, but not always. I've got a couple of threads going, where I've mentioned that cal hypo can be used to REDUCE calcium levels. But it involves that whole 'tweaked pH', upstream of the skimmer dosing thing that I've danced around for years -- because it can be dangerous if chemicals get mixed up.

If you just dump it in the pool, per the label, yes, it usually raises calcium levels. (I suspect, but haven't tested, that it will LOWER calcium levels somewhat if you cloud the heck out of the pool, then push the pH up a bit and filter or vacuum the cloud out.)