A simple solution is to install a tube type membrane diffuser in the well water supply line and deliver the well water, oxygenated to the bottom. There will be a greater absorption of the O2 and fewer bubbles left to rise and mix the cooler water being delivered.
The tube diffuser could easily be sealed inside the water pipe, yet remain easily serviceable. If the gasses not being released are a concern, the described method could still be used by adding the tube diffuser near the well, dumpinng the water into an open top barrel 3-4 feet above the pond surface level as a vent and then letting the unpressurized water gravity flow to the pond bottom.
