This is an improved version of a classic set as it includes an advanced UV unit that sits snugly on the back of the filter box. It is suitable for goldfish ponds up to 9,000 litres (2,000 gallons) and koi ponds up to 4,500 litres (1,000 gallons). The flow-through pond filter included offers all the features of similar products costing twice the price! This set contains the following components (please click links below for more information): • PondXpert UltraFlow 6000 pond pump • PondXpert MultiChamber 9000 flow-through filter • PondXpert Greenstop Pro 36w UVC * Saving made when compared to buying items separately.