Abstract: An air stone suitable for use in aerating water in an aquarium is formed of a body of porous material permeable to air. Included within the body is a central chamber having an inlet port for receiving a connector, the chamber extending beyond the port to form a plenum for distribution of air throughout the air stone. In an embodiment of the air stone constructed with a circular cylindrical configuration, the plenum is enclosed by a cylindrical wall of porous material and closed off by an end wall of porous material. The cylindrical wall has uniform thickness equal to the thickness of the end wall. The connector includes a nipple extending into the chamber to make a press fit for securing the stone to the connector. A similar nipple directed in the opposite direction secures the connector to an air-supply tube.

Abstract: An external aquarium filter having a housing which is mountable onto a wall of an aquarium tank. The housing includes an intake compartment and a filter compartment which in turn includes a contaminated water chamber receiving contaminated water drawn into the intake compartment from the aquarium tank and a filter chamber for filtering the water. A motor unit supported at the filter housing has an impeller which sits into it depending from a collar which fits into the intake compartment of the filter. The impeller draws water from the aquarium tank into the intake compartment of the filter. The impeller is encased in a tubular collar. The tubular collar has two opposing windows. The window, which faces the front wall of the intake compartment, is offset in a clockwise direction, as viewed from above, relative to the window which faces the rear wall of the intake compartment, to effectively close off the right edge thereof, to thereby reduce turbulence in the water flowing in the filter.

Abstract: A heater for heating water in an aquarium tank is provided with a thermostat which includes a bimetal strip carrying one contact and another strip carrying another contact. Upon deformation of the bimetal strip in response to temperature changes, the contacts are closed to connect the heater with an electrical supply circuit. The distance between the contacts is initially set by a rotatable cam acting on a curved portion of the bimetal strip. A cylindrical body which supports the cam to rotate the latter is provided with a helical groove in which is engaged an indicator captured in an elongated axial slot formed in a support of the cylindrical body. The support has at least one scale on its surface visible through a glass container of the heater. When the cam is rotated to change the distance between the contacts this change is indicated by the position of the indicator on the scale.

Abstract: An aquarium accessory for removable attachment to the top rim of an aquarium tank. The accessory includes an instrument useful for the functional or aesthetic benefit of the aquarium tank. A coupling arrangement is connected to the instrument. The coupling arrangement includes a clamping screw for securing to the rim. Coaxillay arranged with the claimping screw is a biting device positioned on the coupling means for biting into the rim upon securement by the clamping screw.

Abstract: An external aquarium filter of the canister type formed of a flat, substantially cylindrical container with a screw-top cover. Both inlet and outlet ports extend through the cover. The inlet port continues with a depending tube to be in flow communication with the bottom of the container and the outlet port is in flow communication with the top of the container. A sheet of foam filtering material is supported in the middle of the container to define a contaminated water chamber beneath the filtering material and a clean water chamber above the filtering material. An air pump or water pump can be used to provide the continuous flow of water through the filter. The water pump can be integrally formed on the cover and include an encapsulated stator, whose housing is integrally molded with the cover. A magnetically coupled impeller is positioned within the outlet flow path to aid in the flow of water through the filter.

Abstract: An undergravel filter of an aquarium tank served by a power head to suck water from a chamber located beneath the undergravel filter to circulate this water into the tank. A riser tube connects the filter with the power head and contains a carbon cartridge, fixed to the power head. The carbon cartridge is perforated and has a substantially conical configuration. The cartridge is filled with carbon which provides chemical filtration of the water before it is returned into the aquarium tank.

Abstract: A filter cartridge comprising a framework and a surrounding envelope of filter material. The framework is reusable and provided with a rough, granular surface texture to provide increase surface area available for the propagation of aerobic bacteria. The envelope is disposable. Thus, biological filtration of the water provided by the aerobic bacteria is not interrupted upon replacement of the filter material. A second filter medium may be disposed within the envelope. The envelope is held in place by a pair of flaps which sandwich an edge of the filter material.

Abstract: A rotor impeller assembly for use with an electomagnetic stator unit including a shaft with a magnetic rotor directly mounted on the shaft. An impeller unit is rotationally mounted with respect to the shaft. A clutch between the magnetic rotor and the impeller unit rotationally drives the impeller unit by means of the magnetic rotor. The magnetic rotor is formed as an injection molded magnet. The impeller unit is used within an aquarium filter for drawing water from the aquarium tank into the aquarium filter for filtration and discharge back into the aquarium tank.

Abstract: A bottom aquarium filter for an aquarium tank including a substantially cylindrical container having an inwardly directed concave forward wall. A grill wall is removably coupled onto the concave forward wall and defines therewith an inlet chamber. A removable L-shaped insert member includes a substantially circular perforated platform wall and an upstanding convex partition wall. The platform wall spacedly sits on the bottom of the container and defines with the container a filtration chamber above the platform and a clear water chamber beneath the platform. The partition wall mates in opposition against a rear peripheral section of the circular wall of the container and defines therewith an air lift chamber. A removable cover mounts onto the container and includes a mouth aligned with the air lift chamber. The cover serves to retain all of the members in unitary assembly.

Abstract: An aquarium filter having a housing unit for mounting on the wall of the aquarium tank with an intake chamber for receiving contaminated water and a filtering chamber for filtering the contaminated water and passing it back into the aquarium. A removable intake tube transfers the water from an inlet end to an outlet end where it can flow from the aquarium tank to the intake chamber. A slidable control valve selectively exposes bypass ports on the outlet end to regulate the flow rate of the aquarium water from a maximum down to shut-off, and all values therebetween.