Ventilating the headspace is the best answer.
Turning on your aeration fans may not be the best plan when it’s humid or if you want to keep the temperature below 40 degrees F. If you can ventilate your headspace, that’s really the answer.
That’s when exhaust fans come in handy. Their job is to remove the moisture from the headspace, not to aerate the grain.
It’s unusual to have sweating in a concrete tank, but it does happen.
If you can open a manhole at the top, maybe even set an exhaust fan on top of the open manhole, then you can move some of that moisture out of the headspace.
Reprinted from Grain Journal July/August 2020 Issue