In an aspect of the invention, a device for purifying water in a water water garden or fish pond comprises a filter medium configured to clean the water flowing through the device, and a housing configured to contain the filter media. The housing includes a wall configured to whirl the water flowing through the device to remove suspended particulates from the flow. Liquid flows into the housing, is turned by the wall to whirl the water about an axis, and exposed to elements held by the filter medium for cleaning the liquid. The liquid then flows out of the housing. Cleaning the medium is performed by opening a drain port and adding water to the chamber.