I would prefer to run large diameter pipe (maybe 1.25" diameter poly pipe) for the hundred or so yards from the barn to the pond,
One source of tubing that is reasonable priced is the black water pipe that comes in 100' or 500' rolls and in various sizes. There is a better grade that works for higher well pump pressures and a cheaper low pressure grade. Either one should work well for aeration as you would normally be working well under 10 psi. The cheaper version is often not available from plumbing houses but sometimes they have both. This vinal water pipe is available from most large plumbing wholesale suppliers and is also available from Lowe's and Home Depot in the section where they sell the supplies for home well systems. It usually is not in the regular plumbing section but where the well plumbing is.
The places that sell aeration also have the non-sinking pipe which I'm sure is fine. The reason I mention this water pipe is in our case the other requires ordering it and waiting a week for it to arrive. I can go to the local plumbing place and get what I need when I need it. It is also cheaper than what the aeration places sell and may even be heavier stuff.
Just another possibility if you find you come up short on pipe length.
