This Pond Filter kit will filter ponds up to 15000 litres. They all have the "EasiCleanse" backwash cleaning system. Included as standard, specially developed profile foam, Japanese pond filter matting, plastic bio media and low voltage ultra violet system. You can bury them to hide them or have them far away, sited in the shed, garage or greenhouse. The UV is low voltage for safety and comes complete with outdoor transformer. They are very user friendly. 15000 model has an 11 watt UV , Clearwater Guarantee.