I do have a fan (warm) but i use it to regulate the heat when the lights are not on it drops to 20 or so, so i set the thermostate to keep it at 28, I shall purchase another do you suggest i leave it on permanitly? or just when the lights on?

I am hoping to sex the plants next week and cut down the number, though the lights do give off over 3,000 lumuns per sq foot (according to my calculations )