I have the same kind of pond. Research Gast rotary vane compressors. You need 1.5 to 2 cfm at minumum 5 PSI, which is about 10 ft water. You can start with a soaker hose coiled up in a 5 ga. bucket.(10 ft or so) Put some large gravel in it to keep it down. Later, when you get a round rubber diffuser, you can add 2 pieces of pvc in an X near bottom of bucket to keep it from tipping. It has done wonders for my water condition in 2 months in an old pond. With all the nutrients from felled trees and grass mowed in the upper hollow, it would have been covered with grass, moss etc, if not for this. The cost of running the compressor will be about $10-15 per month, if run 24/7 which I suggest all summer. The fish will love you for it and grow big for eating. C & S sales on line has a small compressor to get you started for $40 bucks. This one runs on negligible electricity.
