I just posted this pic on another thread but it seems appropriate here too.

Thats a 24" 4 bulb T5 HO on the bottom with 24" T8's on the sides. The Troublemaker mother on the right vegged it's whole life in here and it's a serious bush. The T8 up top is all that's needed for clones.

Air intake is passive (see the holes I drilled), 120mm A/C fans top & bottom for exhaust, temps stay 75 - 78. Since this pic was taken I put another T5 up top with a bubbler for starting seedlings off. Temps are still fine so far.