Calcium

[waterbear]

Biggest problem with calcium cabonate is the solubilty vs. calcium chloride. Calcium carbonate is also what we call "scale deposits" and if you have ever has them on your tile line you KNOW that they are hard to remove . Eggshells are about 95% calcium carbonate and marble is just about all calcium carbonate and they will not dissolve in normal pool water (at least I hope the marble doesn't or my spa spillover is going to have some MAJOR problems )."Lime: is actually either calcium carbonate or calcium oxide and calcium oxide would most likely play havoc with the pH