A water cleaning facility for use in an area of water of less than three meters depth such as in lake, pond, river or reservoir. The device comprises a tube 1 held vertically under water by means of a weight 6 and flotation collar 2. Compressed air supplied to an inlet 16 forms bubbles 22 which rise up the tube 1. The chemicals to be dispersed e.g. aluminium chloride or polymer coagulant and an algicide such as copper sulphate or copper chloride, may be contained within bags (68) located in a framework (67) attached to the top of the tube 1 by cables (65) and provided with flotation means (64. fig.6).