Yeah Bill,
I plugged the 4cfm scenario into my CH 80 gal compressor (with a real motor)
If I crank it up to 175psi, it will pee out 4cfm for 28 minutes, then the tank is down to 20psi. Compressor kicks in at this point with the light bulb dimming effect at first, then runs for 8.5 minutes to recharge, while eating about 800+ watts of electricity.
You'll also need some fancy hardware and filtration to make this work properly, which will be expensive!
Expensive to set up properly + eats electricity.
I like to use my compressor as a labor saving device, which that is what they are intended for. Don't want to fork that kind of cash over to the electric company, or in repairs, to blow some bubbles in water.
A proper aeration system would be a much better choice.
