Abstract: A submersible centrifugal pump especially for aquariums includes a motor driven impeller for circulating water through the pump and a movable flow indicator visible from the exterior of the pump for visually indicating the water flow rate through the pump. The impeller is mounted on a hollow motor shaft which protrudes above the pump to provide for the passage of air down through the shaft for mixing with the water within the pump. The shaft is rotatable relative to the impeller to permit turning of a valve shutter connected thereto relative to a valve seat for controlling the water flow rate through the pump.

Abstract: A thermostatically controlled electric heater for aquariums includes within an electric waterproof envelope, a heating element and a working unit regulating the temperature, moving axially in order to vary the rest position of a bimetal strip which, depending on its deformation, opens and closes the supply circuit of the heating element. The regulation unit (3) is provided with a threaded pin (13), the end resting against the bimetal strip (7) and with a cylindrical body (11), provided on the side surface with a helical line (12) dividing the surface of the cylindrical body into two differently colored portions (12) covered by a screen (18) provided with a longitudinal slot (19) through which a short portion of said helical line (12) is visible. A grauated scale is provided along the slot and cooperates with the visible portion of the line to indicate the set operating temperature of the heater.