Seachem PhosGuard Phosphate and Silicate Removal quickly removes phosphates and silicates from marine and freshwater aquariums. Although it is effective in both freshwater and marine water, it will work best in marine water and its necessity is better defined in marine water. It is not recommended for phosphate-buffered freshwater (PhosGuard would remove the buffer until saturation) Seachem PhosGuard is highly porous and bead-shaped to promote easy water flow through and around it, increasing its efficiency and capacity. How to use Seachem PhosGuard Phosphate and Silicate RemovalThe aquarium filter media may generate heat upon initial contact with water. Moisten by adding to twice its volume of freshwater, followed by rinsing. For best results, Seachem PhosGuard should be rinsed before use and placed to maximise water flow through it, but not so that it tumbles against itself during flow. It can be used in a cartridge filter, media chamber, canister filter or any high-flow area of a trickle filter. The use of a filter bag is recommended. Use 85 ml (1/3 cup) for 200 L (50 US gallons) of saltwater or 400 L (100 US gallons) of freshwater. Leave the aquarium filter media in place for 4 days, then test phosphate or silicate concentrations. If the concentration has not dropped to around 0.02 mg/L, replace PhosGuard, otherwise leave in place until levels begin to rise again. As long as concentrations remain under control, the filter media is not exhausted. Excessive treatment is not recommended. PhosGuard is not an exchange resin and does not release anything into the water. It does not retain phosphate or silicate in the water and can be removed, dried and reused until exhausted. Continuous use of small amounts is preferable to intermittent use of large amounts.