QUOTE (MiijkVanDiijk @ May 9 2009, 10:50 PM)

i am setting up a grow space under the stairs as it is the only space i have available. i have divided the space into 3 segments and i plan to put cuttings under a fluoro light in the smallest, vegging under 250w blue enviro in the middle and flowering under undecided light(probably 250w red enviro because might be too enclosed for HID) in the biggest bit.
Makes no difference - a 250 watt lamp is a 250 watt lamp and you're putting 500 watts of heat into an enclosed space.
In practice, ventilation in the first instance is for the pong - a successful 250 watt grow -
even a fluorescent (and I'm afraid they are a very poor investment compared to a 250 watt HPS), will stink your house out.... in the process of dealing with the pong, you will also have provided the plants with the air they need ... and 500 watts is a substantial amount of heat to shift.