DIRECTIONS: Use one bag for each 120 L (30 US gallons). For best results, PhosGuardª should be placed so as to maximize the flow of water through it. It may be used in a canister filter, box filter, or any high flow area of a trickle filter. Leave product in place for 4 days, then test phosphate or silicate concentrations with either MultiTest: Phosphateª or MultiTest: Silicateª. If the concentration of the component you are trying to decrease has not dropped to around 0.02 mg/L, then replace the PhosGuardª, otherwise leave in place until levels begin to climb again. As long as concentrations remain under control, the product is not exhausted. PhosGuardª does not leach phosphate or silicate back into the water and may be removed, dried, and returned to service until exhausted. Each 100 mL of PhosGuardª will remove up to 20 mg/L phosphate in 120 L (30 US - UPC: 116018500