Drum filters have been used in the water industry and on commercial fish farms for many years, so the actual technology and knowledge isn’t something new. However it’s only in the last several years that drum filters have become readily available to the pond owner and especially the Koi keeper. Drum filters work by first using mechanical filtration – water is passed to the inside of the drum which is surrounded by screens. The water is then filtered as it passes through the screens into the next chamber. The dirt that is left behind eventually restricts the flow of water going through the drum screens which in turn affects water levels within the outer chamber. A sensor then detects this change and triggers a wash cycle. This normally involves the drum automatically turning while being blasted by high pressure water jets from the outside of the drum. The direct is collected in a trap inside the drum and washed away to waste. The screens are capable of filtering out tiny particles making drum filters very effective and efficient. Water then usually passes into another chamber to be biologically filtered (often including a moving bed) before the clean water is returned to the pond. Not only are drum filters very effective and very efficient, they also clean themselves leaving you more time to enjoy your hobby and your fish.