Hi Mactrev & Theo, I believe the comparable Superior windmill to the common 1.5 CFM Koender would cost about $750 from Superior,, The $1400 model Superior is a dual diaphram that produces 3 and Superior tells me up to 4 CFM.I believe Koender has or will have the dual diaphram model also. I believe Mark C. looked into this Koender model.I still advise if you want to stretch your dollar with a windmill get a 1.5 CFM model and use a CoActive airstation instead of a stone and you will turn more water then a dual diaphram model with 3 CFM and two stones as supplied by Koenders. I did notice that Superior supplies a rubber membrane diffuser vs a stone but would appear to be a waste water model that probably produces 1-3 mm bubbles which are still too large and no turnover rates stated. They state you can regulate the air to two and three diffusers but I have never been able to do this with varying CFM output only at constant (wind) output.Check out Superiors site as they do have some good information (some a little outdated) on aeration myths. Mactrev, Im curious what interested you in a Turbo Jet for your 1 acre pond? Bill Cody, how is Koenders coming along with the dual diaphram?? Ted
