You're gonna want a fan over the tops of the plants and under the light.. Then, if the temperature in your room get too hot after the light has been on for a while, it's time to bring in a another fan or two. One at the intake, and another at the exhaust.... From there on its just whatever you have to do to keep the temperatures where you need/want them. The ideal time for lights on is 75F... and ideally you don't want the night to be any more than 10 degrees lower.