looking at a 400w hps, is there anyway use it without a vent system? Like keep it farther away from the plants. or have the light by an open window to get rid of some of the heat?
ventilation is key.. lights do produce heat, some more and some less, my mh light produces a crap load of heat. just make sure you have cool fresh air coming in and a place for stale air to go out like a small exhaust fan or something, put in a wall thermometer or some type of device that reads the room temps and you'll be fine. i find that around 78-80 temp works best for me. hope this helps a little