Working on turning a very small room into a darkroom. I know that's not recommended, but it's what we've got to work with. It's about 7' square, maybe a little longer on one side. It has one window and a door on the adjacent wall, the plan is that the chemicals would be under the window (To help make the ventilation easier) , and the enlargers (a Besseler 23CII and hopefully a Besseler 4x5) would be on the opposing wall. I know we will have long printing sessions, and I know photo chemicals aren't good for your brain. I don't however, have any idea what to look for in terms of venting out the place. Are there vent's/fans built for this purpose or do we have to create some odd light tight fan apparatus thing? How close should the fan be to the chemistry and how powerful should it be? Should there be one in the doorway too for a crossbreeze? What would you recomend for both light tighting the room and the fans/whatever we end up using?