Abstract: An aquarium filter of the free standing, nesting type is provided with an improved magnetic coupling system to couple a drive motor to the impeller which pumps water through the filter. A ring-shaped magnet is secured to the motor shaft and a second magnet coupled to the impeller and carried within the filter housing is inserted into the space inside the first magnet. The magnets are maintained coplanar and the rotation of the motor is coupled to the pump impeller of the filter in a very efficient fashion.

Abstract: A filter cartridge for use with liquids or gases which includes a back structure having a plurality of channels formed in it and filtration granules contained within the channels. Each of the channels includes a plurality of holes to enable water to pass through the back structure. A filter element is secured to the front of the back structure to cover the channels. The provision of the channels enables a uniform distribution of filtration granules to be maintained throughout the filter cartridge.

Abstract: An adapter for a humidifier is provided that mounts on a sealed container of purified or sterile water and connects usually to a flowmeter which is attached to a pressurized gas container. The adapter includes a spike member to pierce the container wall, a pressure chamber defined between the inner wall of the adapter and the spike member, and port means in the adapter wall establishing communication between the pressure chamber and the outside atmosphere. An audible relief valve means is located in the port to effect audible pressure relief under above normal pressure conditions in the pressure chamber during the humidifying process while pressurized gas is being introduced into the water to moisten the gas.

Abstract: A filter apparatus for aquariums consisting of two separable units. Within a filter unit is located the water filtering means and a pump for circulating the water from the aquarium through the filter means and back to the aquarium. Mounted upon a power unit is a motor having an output shaft which at one end is provided with a magnet. The power unit and filter unit are both hung from the rim of a wall of the aquarium by means of interlocking lip structures. The units are constructed such that the filter unit is seated in a "nesting" fashion upon the power unit, thus the power unit and filter unit are positioned in close proximity to one another and maintained in proper alignment such that the magnetic field of the magnet on the motor shaft magnetically influences a flywheel of the water pump and causes the latter to pump water when the motor is energized.