The invention relates to a horizontal agitator for producing a flow in a clearing basin, wherein a propeller (2) having a plurality of blades (4) is connected to a submersible motor (1) axially disposed thereto. In order to increase the efficiency of the horizontal agitator, according to the invention the propeller (2) and the submersible motor (1) are configured such that during operation of the submersible motor (1) a flow (P2) that is directed from the propeller (2) to the submersible motor (1) is produced.