Floor-mounted retrievable lagoon aerators are marketed in the U.S.A. by AerResearch, Inc. and Environmental Dynamics, Inc. They consist of diffuser assemblies with attached ballast which sit on the floor. Sometimes the are offset from their ballast by a spacer device. Characteristics include:

1. Requires a level floor (or spacer device). Note that if a spacer device is used to compensate for uneven floors, there is no way of knowing whether the spacer is the correct length after the aerator has been retrieved and replaced.
2. Pipe can be submerged to avoid exposure to wind, ice, ultraviolet degradation, and vandalism.
3. Aerators remain at the same elevation even if the water depth fluctuates.
4. Operators must handle ballast when retrieving/replacing aerators.
5. Aerators cannot be replaced to original submergence after retrieval.
6. Aerators cannot be replaced to original tip-to-tip level after retrieval.
7. There is no vertical adjustment.
8. There is no leveling from tip to tip.
9. Cannot be installed with water in the basin.
10. Dead-man anchors and tethers to maintain position are not required.
11. A system to maintain tether tension to compensate for thermal expansion and contraction of the air supply pipe is not required.
12. Can be installed offset from the air supply pipe.