Also known as chalk, Calcium Carbonate is suitable for brewing dark beers, which require a CO32- concentration of at least 150 ppm. It is used for increasing Residual Alkalinity in the brewing water as well as raising the mash pH. Additions can be put in the brewing water or directly into the mash.
1 gram of CaCO3 per litre of water contributes:
400 ppm Ca2+
600 ppm Total Alkalinity as CaCO3
20 mEq/L Alkalinity as CO3-2