I know of a new product called AquaKler that may be perfect for your situation. This is a chemical compound that when applied to a water body quickly sinks to the bottom and slowly releases oxygen over an extended period of time. (up to 4 months?) We are conducting several case studies and so far this product has brought up and kept oxygen levels high for almost two months in ponds 1/2 - 1 acre. It's not practical or cost effective yet for larger bodies of water, but for your situation it would not take much to raise the oxygen levels on the bottom of your pond with out disturbing the thermocline. Per the manufacturers request it is only available through our distributors so if your interested contact me and I can put you in touch with the closest to you.
