Pond Boss Forums AERATION Systems questions Soaker Hose

If the pond is mostly 4-6ft deep and it gets good wind exposure, I doubt it needs to be aerated. A fountain would serve this pond okay to keep surface water oxygenated in the area of the fountain during extended cloudy periods and water is soupy green, then DO is likely to be to be lowest at early morning. Your sump pump venturi idea would also work to save a few fish when there is a fish kill occurring or chance of occurrring.

If the water has secchi disk visibility of 2.5ft to 3 ft, phytoplankton and plants will produce DO at the bottom for depths of up to 7ft.
https://en.wikipedia.org/wiki/Secchi_disk
http://www.des.nh.gov/organization/divisions/water/wmb/vlap/documents/secchi.pdf
http://serc.carleton.edu/microbelife/research_methods/environ_sampling/turbidity.html