True, I'm no proponent of using an intake fan, but I do realize there are times that one may be necessary. If you have good exhaust, a simple intake hole, (or two) the same size as the exhaust hole is sufficient.

I have not had any experience in going hydro, and thusly don't want to represent that these 'techniques' will work that way. I try never to comment on techniques I've never personally tried before.
The main thing I'd worry about, tho...is how to keep the reservoir cooled enough not to harm the roots.

Have you thought of using a light mover?