Abstract: It is important healthwise to oxygenate water in swimming pools in order to kill the mainly anaerobic micro-organisms that may come to grow therein. Chemical agents are nowadays in current use, however, they are expensive, and also they do have damaging effects on the tissues of bathers particularly for the cornea. By mounting an oxygenating device at the water outlet of the recirculating system of the swimming pool, growth of anaerobic organisms is prevented. The present aerating device includes a spherical nozzle with a water flow channel, coupled to the recirculating system main water duct outlet, and a straw, engaging at one end transversely into the water flow channel and escaping at the opposite end above the water line. Ambient air is fed to and dissolved in the recirculated filtered water by the venturi effect generated by the forced circulation of water through the conventional recirculating water filtering system.