I have a kiddie pool for my geese. I don't fill it since we dug out the stream. There used to be a creek through here, so we just took out the grass where it appeared to have been and now it's flowing instead of flooding our lower pasture. Anyway, the turkeys liked to walk around in that kiddie pool. Now they use the stream.
I think an industrial fan might be a bit much, though. How big are the turkeys? If large enough, they might use a wading pool, but the enclosure doesn't look like it would easily hold one. I had a regular fan blowing over iced water for my CX last year on the hottest days and that seemed to help.
They seem to be enjoying it. Still look a bit hot. When I make the enclosure larger I’ll put a large tub in there for them and see if they jump in. I know last year my hens would on hot days. I’m in the process of building them a 3-sided coop/roost.
They are 8 weeks old today.