SK, get a Kill-o-watt meter and plug your aerator compressor into it. That will tell you the use of the aerator system only and give you a more accurate idea of what your true electric costs are to run it.
Sue at Vertex (advertiser contributer to this board) can run calculations on your pond size and turn over recommendations. My guess is that in 24 hours about 2-3 heads would still turn it over in 24 hours but don't know all the details of depth and the shape of your pond.
