PhosGuard, 4 L / 1 gal.
PhosGuard rapidly removes phosphate and silicate from marine and freshwater aquaria. It is not recommended for phosphate buffered freshwater. PhosGuard is highly porous for high capacity and bead-shaped for optimum water flow. It outperforms all competing products. 500 mL easily treats over 150 gallons*. This product is sold by volume. Cited weight is minimal weight.