Abstract: Chlorinators are provided for use with saltwater swimming pools. The chlorinators do not require mains electric power and can be fitted to the pool without requiring any significant modification of the pool piping. One form of chlorinator (10) comprises a set of electrodes (18) which are connected to the output of an electric generator (16) which, in turn, is driven by the flow of water produced by the pool pump during filtration. The generator (16) has a shaft on which is mounted an impeller (15) which may be driven by the water flow through the pool return pipe outlet (13) or the water flow in the leaf basket cavity (14). In another form, a generator (36) is mechanically coupled to the pump motor (35). In yet another form of the invention, the electrodes (26) of a chlorinator (21) are mounted on the underside of a floating housing (24) and are powered from solar cells (23) located on the topside of the housing.