Abstract: A surface aerator is provided which includes a float, a throat or draft tube supported by the float and forming a float unit therewith, a power module including a motor and a propeller which is driven by the motor and is disposed within the throat of the float unit, and a mounting ring construction for mounting the power module in spaced relationship above the float unit. The mounting ring construction includes upper and lower rings joined together by a series of upstanding rods. The upper ring is bolted to the power module by bolts which extend into the rods and the lower ring is bolted to the float unit by bolts which extend through circumferentially spaced apertures in the lower ring.