In my recent phone conversation with Koenders, they said their current electric system furnishes 2.2 cfm air, their older systems furnished 1.1 cfm air. Older systems, either electric or windmill supplied the same volume of air. Newer electric systems have a different diaphragm so they are the ones furnishing 2.2 cfm. Windmills still are at 1.1 cfm.
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).