Liquid pump apparatus and method

An apparatus that recirculates liquid in a liquid storage tank, the apparatus comprising:

• an immersion assembly comprising at least one immersion member having a liquid conduit provided therein along at least a portion of a length thereof, the liquid conduit comprising opposite open free ends, wherein one open free end is a liquid inlet aperture and the other open free end is a liquid outlet aperture, and a plurality of liquid outlet apertures formed therein in vertically spaced apart relationship along a portion of a length of the liquid conduit, the plurality of liquid outlet apertures being arranged to allow passage of liquid out from the liquid conduit, and wherein the at least one immersion member is configured to be disposed within the liquid storage tank such that the open free ends of the liquid conduit are within the liquid storage tank, the immersion assembly being arranged whereby in use at least a portion of the immersion assembly is immersed in liquid to be pumped, the apparatus being arranged to provide a supply of gaseous fluid to liquid in the tank through the at least one immersion member at one of a plurality of vertically spaced apart locations of the assembly thereby to cause passage of liquid through the assembly from the liquid inlet aperture to the liquid outlet aperture of the assembly, the apparatus being configured whereby a location at which gaseous fluid is supplied to the immersion assembly is selected to be a location at which a head of pressure of liquid in the tank is within a prescribed range of values.