The Cross-Flow Biofill is a flow-through filter with a large purifying capacity and a strong biological effect. This combined with the simple installation, low maintenance and enormous water filtration makes it universally applicable. With nylon hose nozzles and solid, domed lid.Compact and powerful flow-through filter UV-C unit combats suspended algae and germs Japanese mat removes coarse dirt particles Active carbon absorbs small dirt particles Filtra-Sub for optimum biological filtration Optional: Heating element in the filter Optional: Complete set with pond pump and hose Simple installationConnect the filter to a dirty water/pond pump for the circulation of pond water. Use a filter hose to connect the pump outlet to the inlet of the filter. Attach a second hose to the outlet of the filter for return flow to the pond. Place the filter next to the pond and lower the pump under water. Activate the UV-C lamp and the water flow by inserting the plugs into the socket. Read the operating instructions first!