"State of the art" best describes the Rena Filstar XP3 Canister filter system. The Filstar XP series recently won an industry award for best aquarium filter. What makes this filter so unique? First, bypass-free filtration. This insures that all water passes through the filtration media. This is done with an up-flow filter design that has the added benefit of allowing gravity to settle out larger particles in the bottom of the canister thus reducing the maintenance required on the foam filters.