I have a one acre pond that I dump all my geothermal water to. I've had it for 4 years and I have never oxygenated the water, its a straight dump. With the surface area of this pond, I have plenty on oxygen, and when ever I test it, it's always saturated. I'd be more concern with the quality of the well water that you're using. I live in a farming area, and even though I draw my water from 200 ft down, it's still rich in phorphorus, which creats a host of algae problems. So, from my standpoint, the oxygen level of the well water in minor, the quality of the water should be your greater concern.
