PhosGuard rapidly removes phosphate and silicate from marine and freshwater aquaria. Due to its spherical shape and highly porous quality, it allows maximum water flow and contact giving optimal results. It is not recommended for phosphate buffered freshwater. Directions May generate heat on initial contact with water. Pre-wet by adding to a double volume of freshwater, followed by a rinse. For best results, PhosGuard should be rinsed before use and placed so as to maximize the flow of water through it but not so that it tumbles against itself in flow. It may be used in a canister filter, media chamber, box filter, or any high flow area of a trickle filter. Use of a filter bag is recommended. Use 85 ml (1/3 cup) for every 200 L (50 US gallons) saltwater or 400 L (100 US gallons) freshwater. Leave product in place for 4 days, then test phosphate or silicate concentrations. If the concentration of the component you are trying to decrease has not dropped to around 0.02 mg/L, then replace the PhosGuard, otherwise leave in place until levels begin to climb again. As long as concentrations remain under control, the product is not exhausted. Over treating is not recommended. PhosGuard is not an exchange resin and does not release anything into the water. It does not leach phosphate or silicate back into the water and may be removed, dried, and returned to service until exhausted. Continuous use of small quantities is better than intermittent use of larger quantities.