Abstract: Apparatus for mixing liquid in a container, comprises a hollow sleeve member for location in the lower regions of the container, a plurality of circumferentially spaced outlets being provided in the upper regions of the sleeve member, pump means for creating a reciprocating flow of liquid applied to the lower regions of the sleeve member, and in the flow path of liquid from the pump means to the sleeve member, a transducer mechanism cooperating with the sleeve member and subjected to the reciprocating flow of liquid such as to rotate the sleeve member about its central longitudinal axis in dependence upon said reciprocating flow.