Calcium carbonate is 99% pure...
CaCO3 (lime) with a grain size of 4 to 6 mm (.15" to .23"). It is ideally suited for use in TUNZE® Calcium Automat and other makes of Calcium reactor for buffering the pH value as well as increasing the calcium content.
Calcium carbonate is a hardness granulate of more than 99% CaCO3 (calcium); grain size approx. 4 to 6 mm (.15 to .23 in.); for pH value buffering (increase in carbonate hardness) and to increase the calcium content (Ca2+).