Bill:
An easy way to figure the price difference (operational costs) is to look at how many gallons per hour lifting rate a diffuser (pick a certain one) has. Now figure out how many diffusers could be run from a 1/2 or 3/4 hp compressor, that will give you how many gallons it'll move in "X" time. Compare that to a water pump that will move the same amount of water in the same amount of time.
