mechanical agitation will help a lot to improve oxygen entry into the layers of sediment. In shallow ponds anything mechanical will work (kids feet, boat props, jet ski impeller wash) but in deeper ponds it may be a challenge to get the mechanical means in place. Boats and jet skis are probably a no go.
you do have access by way of scuba so maybe you can take a roto-tiller down there
I imagine a trash pump with a long hose guided by a weighted scuba attendant might work but once you start stirring things up visibility is going to be about zero at the bottom.
Maybe a auger/post hole attachment on a 70 foot shaft to go up and down?
Too bad you couldn't rig up an oil well type apparatus with the big counterweight, and have the business end include a section of galvanized pipe with a big heavy dumbell shaped weight on the bottom. A small electric motor could start moving the oil rig up and down so that it could plunge the heavy weight and disk shaped end down into the sediment and then using the counterweight lift up and down. Of course that would ideally be boat mounted and not shore mounted.
Your depth and quarry size are the hurdles here...
It is so encouraging to hear how much you improved conditions for fish and scuba enthusiasts alike! Too many people I talk to feel that all you need to do is put a pretty fountain on top and call it good for aeration
