definitely need a good fan-cooled hood, or a fan-cooled light tube ... I'm running a 250cfm duct fan thru my 400-watt HPS, and it still needs MORE airflow ... that is in addition to an exhaust fan, and an oscillating fan inside the cabinet ... canopy temps around 85-90 daytime, 75 at night ... I don't get too excited about it, my plants are thriving, regardless ... I will add bigger fans, if I ever get around to it (too stoned to bother)