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.