Pro-Carb Z is the ideal blend of Pro-Carb and Pro-Z Laboratory-Quality Activated Carbon and Ammonia-Removing ZeoliteCrystals. Pro-Carb Z works to remove harmful chemicals,toxins,odors,discoloration,and other contaminants while giving your aquarium a crystal clear look. Recommended for use in Cascade,and all other hang-on,internal and canister filter systems. 64 ounces.