One embodiment of an aerator is disclosed that has a hollow intake housing with a horizontally disposed lip on a lower portion thereof. This intake housing converges a flow of bubbles into a draft tube. These bubbles are injected into a fluid in which the aerator is installed at a location that is directly under the intake housing. A fluid flow is also drawn into this draft tube through the intake housing. Fluid exiting the opposite end of the draft tube is directed into a hollow discharge housing having a divergent inner surface. A wave generator (e.g., a rotating impeller) is mounted within the hollow interior of the discharge housing. The upper end of this discharge housing also includes a horizontally disposed lip to direct a flow out of the aerator at least generally parallel with an upper surface of the fluid.