If you are looking for the best koi filter on the market then here it is! The nexus 320 is designed specifically for larger koi ponds it can handle koi ponds up to 34,000 litres 7,500 gallons.the nexus eazy breaks the mould as far as pond filters are concerned with a revolutionary approach. Dirty water enters the filter's inner chamber which acts as a vortex allowing larger solids to settle out. Finer particles get caught in the eazy chamber full of static kaldnes biomedia. Water then flows to the bubbling oxygen enriched outer chamber, before clean water returns to the pond. To clean the filter simply turn the direction of air flow from air pump supplied from your pond to the filter the biomedia 'bubble up' releasing the dirt and this dirty water exits to waste. Once water looks clean simply redirect the flow of water and air back to the outer chamber. Simple and no need to get your hands dirty!no wonder this product has made such an impact on the fishkeeping market, it's simply brilliant. In order to operate successfully the nexus needs an air pump and we can think of none better than the evolution aqua airtech 130 usually £249.99.buy this kit and save yourself sixty quid!