Buying calcium -- this is ridiculous

[chem geek]

Paul,

It's Calcium Chloride, not Calcium Carbonate. It comes in two forms, Calcium Chloride Anhydrous such as found in Peladow (90% pure) and another form Calcium Chloride Dihydrate such as found in Dowflake (96% pure). It is also, of course, found in many "Calcium Hardness Increaser" products at pool stores. You can also buy it at The Chemistry Store.

Richard