Provide up to 25X the buffering power of other crushed corals dolomite and oyster shell with CaribSea Flordia Crushed Coral containing aragonite! Combat chronic pH problems and maximize water purifying bacteria surface area with this product that can increase bioload by 50% without ever needing to be replaced. When used with calcium carbonate buffer and strontium up to 10 000 ppm are also provided. Grain size: 2.0 -5.5mm just lightly rinse before use.