ION EXCHANGE FILTER PARTICULARLY A MINIATURE FILTER

The filter includes a container filled with ion exchange material and has an upper opening, with the liquid to be treated flowing longitudinally upwardly through the container from a bottom inlet. The container has a bottom wall and sidewalls extending upwardly from the bottom wall and with upper ends converging inwardly to the upper opening. At least one plate, having lateral dimensions substantially equal to the inner lateral dimensions of the container adjacent the bottom wall, is positioned on the bottom wall and has openings for the passage of liquid to be treated. The plate is formed of material which is sufficiently flexible to provide for the plate to be inserted through the upper opening into the container. In one embodiment of the invention, a single flexible plate has elevations on its surface toward the bottom wall, spacing the plate from the bottom wall. In another embodiment of the invention, a second plate of sponge-like material is positioned on top of the first plate. In a third embodiment of the invention, only a plate of sponge-like material is used and the inner surface of the bottom wall is formed with a series of concentric discontinuous annular ribs.