The invention described herein is drawn to a hollow cylindrical filter for use with a suction canister including a first portion having an open end and a first wall thickness, a second portion having a closed end and second wall thickness less than said first wall thickness, and an elongate central chamber having a substantially uniform diameter along its length. The filter is composed of a composite material including a porous plastic material and material adapted to increase the viscosity of a liquid coming into contact therewith. The filter is constructed to accommodate the changes associated with air flow velocity and shear force across the filter material as the fluid level in the canister rises, and automatically shuts off the vacuum to the interior environment of the suction canister. The invention also includes a filter system including such a filter in combination with a filter shield which accommodates the filter within and attaches to, or is alternatively integrated with, the underside of a suction canister lid.