Seachem PhosGuard 2 Liter. Is a high capacity and high efficiency filtration product for removing phosphates and silicates from marine and freshwater aquaria. Unlike competing products, Phosguard is bead-shaped for optimum flow characteristics and has an exceptional porosity for enhanced capacity. Phosguard has a working capacity to remove 20 to 60 mg-L of phosphate in 400L (100 gallons) with a similar impact on silicates. It may be used continuously or intermittently, and will not release removed phosphate. Each liter treats up to 1200L (300 gallons). Marine and freshwater