I'm with Bill on the renovating. If you elect not to renovate, then you might not need any aeration whatsoever because the O2 might go deep enough without aeration like he said. I did a pond consultation a little bit ago for a Homeowners Association. water clarity was 6', there was a thermocline at 7', the level of O2 that was high enough to support fish disappeared below 8' depth.

If you elect to run electricity to the pond, make sure you use large enough wire or you run the risk of burning out whatever pump/compressor you put at the pond. Remember that it's not the running amps but the starting amps that you have to watch, and also calculate the amount of current drop over that length of run. If I was running electric to the pond, I would make sure that I ran enough wire for 220 volts.