Hey Aussie. Your situation is very similar to mine. My pond is a little smaller but about the same depth. I angled my sweeper nozzle down about 1 or 2 degrees. Just enough to keep it from wasting some of it's energy in splashing. Ask NEDOC...just that one nozzle would turn the water in the little pond. I tested DO a couple of times and it improved dramatically.
I think aeration is achieved in several different ways, acting in harmony. First of all, the pressure stirs the water, which increases the net surface area which is exposed to the atmosphere over time. Secondly, the cooler water in the well is heavier that the warm surface water in which it is discharged. This heavier water near the surface has to drop and this creates a subtle turnover effect. In addition to this, some ponds are so protected from wind that on calm or near calm nights you get a protein skim on the water's surface which limits gas transfer into the water column. Lastly, the pressure as the water enters the pond creates an atmospheric downdraft which literally puts thousand of bubbles into the water column. It worked immediately, and prevents me from having to run an aerator in this pond. I've done some research on the internet and found a couple of references to Thailand shrimp farms that use circulation instead of aeration and they are able to produce an unbelievable quantity of shrimp per acre. Just astounding!
If you didn't run it 24/7 I think that nighttime would give you the most benefit.
