ViaAqua Poly-Reactor Multi-Media Reactor is built with high quality acrylic and an easy to remove lid with a recessed o-ring. The reverse water flow design eliminates water channeling through the filter media thus efficiently utilizing filtering media. ViaAqua Poly-Reactor comes complete and ready to run with a pump and all plumbing parts. It is designed to be installed either in-sump or hang on the tank.