My pond is not 20’, closer to 15+. I’ve not added aeration due to long distances from electric, and high cost of a good solar system. Our little BOW is only 4 yrs old, but it’s producing great fishing. Lots of fun swimming time, and is a pleasure to just sit by it.
I’m sure I’m gaining sediment in the bottom, as it’s ringed by tall timber. I may be paying a price later for not aerating, but only time will tell.
I also have on again, off again drought conditions, and a small leak, so when it’s down 4’ I think I’ve still got enough water for healthy fish.
I did go with steep banks to keep water plant production low, but then you almost have to build a dock in order to get out of the water.
Jeff

9 yr old pond, 1 ac, 15' deep.
RES, YP, GS, FHM (no longer), HBG (going away), SMB, and HSB (only one seen in 5 yrs) Restocked HSB (2020) Have seen one of these.
I think that's about all I should put in my little pond.
Otter attack in 2023