Suitable for ponds ranging from 18,000 litres goldfish to 9,000 litres koiat last, a genuine multi chamber professional filter box that anyone can afford. The pondxpert multichamber 18000 flow through pond filter offers the features found on similar products but at a reduced price!easy maintenance simply lift the lid and pull out the foams by the handles. The foams can then be squeezed clean.sludge outlet this gravity filter comes complete with an integrated sludge outlet on each chamber, which can be used to remove sludge from the base of the filter or do a back flush!high quality filtration the multichamber systems include both coarse and fine foam filtration along with a layer of japanese matting at the bottom of each chamber.built in thermometer a handy, replaceable thermometer is attached to the lid, giving you an accurate reading of the pond’s temperature.please note this filter does not have a uvc.