PhosGuard by Seachem Laboratories is designed to swiftly eliminate phosphate and silicate from both marine and freshwater aquariums. It is not suitable for use in freshwater systems with phosphate buffers. Featuring a highly porous structure for maximum effectiveness and a bead-like shape for enhanced water circulation, PhosGuard surpasses other similar products in performance. A 500 mL container can efficiently treat more than 150 gallons*. Note that this item is sold by volume, and the stated weight represents the minimum. Available at shop.morphmarket.com.