Patent ID: 6843909

Claim:
A filter unit for filtering aquarium water through three stages of filtration, including mechanical filtration, chemical filtration and biological filtration, the filter unit comprising: a packet having porous filter walls with peripheral edges including longitudinally extending side edges and laterally extending end edges, the filter walls being juxtaposed with one another and configured for mechanical filtration of aquarium water passed in a generally transverse direction through the filter walls; a filter medium interposed between the porous filter walls, the filter medium being configured for chemical filtration of aquarium water passed through the filter walls in the generally transverse direction; a block of reticular material for juxtaposition with the packet in a location wherein aquarium water passed through the filter walls of the packet in the generally transverse direction will be intercepted by the block of reticular material, the block of reticular material being configured for biological filtration of the aquarium water passed through the block; and a frame for securing the packet and the block in juxtaposition with one another in an integrated unit, the frame having transversely opposed frame members including openings distributed longitudinally and laterally throughout the frame members for passing the aquarium water through the frame members to enter and exit the filter unit along the generally transverse direction.