This large professional pond filter set up is suitable for goldfish ponds up to 18,000 litres (4,000 gallons) and koi ponds up to 9,000 litres (2,000 gallons).. Both bays of the filter contain foams, one of which is a coarse blue foam and the other a finer yellow foam, which catch all but the tiniest debris particles. This set contains the following components (please click links below for more information): • PondXpert UltraFlow 10000 pond pump • PondXpert MultiChamber 18000 flow-through filter • PondXpert Greenstop Pro 36w UVC * Saving made when compared to buying items separately.