That latest science in Calcium availability, the powder is your typical Gh and Kh African Cichlid salts but the block is a slow release non clouding form of Calcium Hydroxide. Normally this can't be utilised outside of a reactor. The block compliments the powder by slowly realising and converting C02 into bioavailable Calcium bicarbonate at the same time buffering pH.
Calcium Bicarbonate is one of the only forms of bioavailable calcium that also increases pH and kh. This happens depending on Bioload and water change frequency. Its also very useful in tanks that experience hard to control pH acidification and assists aquarium stability.