My new pond is about 120 x 60 feet 6ish feet deep. Can I aerate full time. The pond is kind of figure 8 shaped. I was thinking 2 diffusers. How do I make sure I don't over do it. I'm adding minnows this year other fish next spring.
It's gonna be a pretty place once the plants come back and the water clears.
I'm no expert, but in your shoes I'd wait for the water to clear & it is stocked before aeration. Also you need to read threads about aeration, it is very easy to do it wrong and kill your fish!
I would agree with anthropic and wait for it to clear up just so you know that it will. Aeration will slow that process down and you should not be in a hurry to aerate at this point if your stocking gamefish next year. Read and read some more on the aeration topics here at PB, they are most helpful.
Two diffusers should be fine so long as you size the pump appropriately. In fact, small ponds like ours (mine is 100 by 170) would do just fine with 1 diffuser running at its maximum output. I am sure that I could run 6 diffusers in my pond and do it good, but 3 will work just fine and it reduces the possibility for a larger pump.
I believe the biggest benefit to aeration is putting oxygen into more of the water than there would be without. This allows for more pounds of fish to live well in the pond and it also helps the bacteria and such to breakdown the wastes that accumulate on the bottom. Your pond is new and does not have fish. I would take my time and plan to install the system about the time your stock your gamefish. It would not hurt to do it earlier however IMO.
If I had it to do over again I think I would commission the aerators before I stocked my fish merely so that I acclimate the fish to the completed pond. I put fish in first then installed the system and it has caused another "thing" for the fish to get used to. It has not been a big deal at all, but I think it would have been a little better if the system was in the pond a month before adding fish just to avoid them having to get used to it after the fact.