Pro-Carb Laboratory Quality Activated Carbon is fast acting, long lasting, and designed to keep your salt, or fresh water aquarium crystal clear for up to 4-6 weeks, Features: , 25 lbs in poly bag, Carbon removes harmful chemicals, toxins, odors, discolorations and other contaminants, Recommended for use in Cascade, and all other hang-on internal and canister filters SKU: EPPBC25