I'm running leds. 250w cree cobs in veg and 440w luminus cobs with 120w monos plus 60w far red after lights out. Venting into my apartment two 4 inch 200cfm carbon filters to a 6 inch 420 cfm fan. Two steel cabinets 2x4x6.5. My fan comes on for about 45 seconds every 15 minutes it's on a thermostat.