OK, Check out the video. Mr.Lusk talks about an example at 21:58, again at 56:40 AND the general rule of thumb at 1:00:48.

Watch the whole thing...your brain will grow substantially regarding the space allocated for pond aeration....

https://www.pondboss.com/news/facebook-live/7_18_18--aeration-in-summer-months-with-matt-rayl

Fish on!,
Noel