Fluval Phosphate Remover for 07 series are designed specifically for the Fluval 07 series external canister filter series, Phosphate Resin infused Pads perform double duty as both an effective mechanical and chemical media. Often a strong algae growth is caused by too high phosphate values. If after a test it is established that the phosphate value of the water is too high, this filter pad can be used to react quickly. If the filter pads are used preventively, high phosphate values cannot even occur in the first place.Fluval Phosphate Remover for 07 series+ specifially desgined for Fluval 07 series external filters+ for 107/207/307/407+ controls phosphate to reduce algae and green water+ use as many pads as necessary to reduce and control phosphate levels+ effectively traps floating particles for clear water (debris, excess food and waste)+ prevents potential algae outbreaks+ custom fit to increase filtration efficiency+ for best results, replace monthly or as required after testing wa