Update to the OP.
I ended up purchasing this system with two airstations:
https://easypro.com/products/sentinel-deluxe-aeration-system-complete-pa34-2-system-with-cabinet/The EasyPro people thought that one airstation was sufficient for my application, but I went with the two airstation model for more flexibility. At 1/4 HP and 2.3 CFM, this is probably the bare minimum for my pond size. We shall see.
EasyPro is a Michigan-based company. I got a really good deal from a retailer. I thought this was a nice compromise between the cheap Chinese system I was looking at originally and the top of line brands.
