There's nothing in your bathroom that's going to make any difference to the plants. You don't need to put a carbon filter on your intake or any filter period if it's pulling from inside the house.

I run 800w right now in a 4'deepx6'widex7'tall closet, made up of two 250w halides and two 150w hps's with all the ballasts in the same closet. My only exhaust is a bathroom exhaust fan of unknown but certainly very low cfm. (much much lower than any squirrel cage fan or can fan) I can close the door to the closet and keep temps around 90, or keep the doors open and then the closet and my bedroom go into the 80's and 85f range.

If I had a problem with the temps I would have put the ballasts in the attic and then I think it would be a different ballgame.

Anyway all those lights do create a lot of heat, well over twice what a single 400hps would. If you can afford a good fan get it, if not you can get by with very little like I am. If you set the lights to be on during the day and off at night so you can sleep and it's not hot when you're in there you'll be set either way.

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