A sludge filter is comprised of a mesh filter media secured to a support net. The support net includes a front surface adjacent the filter media and a rear surface opposite the filter media, the rear surface having a plurality of outwardly extending nodes to define flow channels for horizontal and vertical fluid flow intermediate the net and a container surface. The sludge filter is attached directly to the walls or floor of a container. In a preferred embodiment a border of the sludge filter comprises one part of a two-part fastener system with a second part of the two-part fastener system attached to a container along the perimeter of the filter coverage area, so that the filter medium may be removably attached to the container.