Apparatus for mixing and introducing gas into a large body of liquid

The disclosed device herein relates to the field of aeration and mixing of large bodies of fluid. More particularly, the present invention is an improved apparatus for the introduction of gas and dissolved gases into a large body of liquid and for concurrently providing the ability to mix the liquid in a large body of liquid. An gas diffusion device for introducing gas into a large body of liquid having at least one diffuser blade that engages over a mounting tube having a spar affixed to its exterior. A passage in the diffuser blade is dimensioned to cooperatively engage over the spar and mounting tube which holds the diffuser blade top surface at a determined angle once so engaged thereover. Changing the position of the spar on the exterior of the mounting tube in relation to the center axis of the mounting tube changes the resulting angle of the diffuser blade top surface. The diffuser blade can be attached to a hub mounted on a mainshaft that automatically cantilevers out of the fluid should compressed gas supplied to the diffuser blade through the mainshaft cease to avoid damage to the diffuser blade and diffuser pad on the blade from particulate in the liquid.