Perfect for small koi ponds up to 10,000 litres (gallons) or goldfish ponds up to 20,000 litres (2,000 gallons). The Eazypod breaks the mould as far as pond filters are concerned. Dirty water enters the filter and heavy solids are forced down and out by the vortex created by the cylindrical water flow.Finer particles get caught in the static Kaldnes biomedia. Clean water then returns to pond. To clean the filter simply turn the direction of air flow (you need a 70 litres per minute air pump not supplied) from your pond to the filter - The biomedia \'bubble up\' releasing the dirt and this dirty water exits to waste. Once the water looks clean simply redirect the flow of water and air back to your pond. SIMPLE - and no need to get your hands dirty! No wonder this product has made such an impact on the pondkeeping market, it\'s simply brilliant. PLEASE NOTE THIS FILTER DOES NOT HAVE A UVC