A bubble injection system for forming and distributing micron size gas bubbles in a body of liquid at the point of use of the bubble distribution comprising an axially extending inner fluid conduit forming an axially extending liquid flow channel and a concentric outer fluid conduit extending axially along the inner conduit and spaced therefrom. An outer gas channel is defined by the conduits and includes a plurality of porous outlets extending thereacross from the inner conduit to the outer conduit. The porous outlets terminate in outlet jet ports spaced along the outer conduit whereby gas flowing through the gas channel will penetrate the porous tubular outlets to form gas bubbles and liquid floring through the liquid conduit and outlets will sweep the gas bubbles from the surface of the outlets toward and out of said jet ports for immediate dispersion of the body of liquid.