tent set up i

I have the 2 by 2 foot tent and need some help with set up. I have a chhc 4 environmental controller but my problem is cooling the tent I have a 400w light and gets pretty hot in the tent I need a way to vent my tent without wasting co2. I am thinking that if I hook my fan up to my chhc 4 the fan will stay on consistently and the co2 won't kick on due to the design on the unit (co2 will only turn on when the exhaust fan is off) I was thinking of venting the hood directly all times the light is on but I don't want to waste co2 from the hood leaking; it is a sealed hood but let's face it everything leaks. I havnt used co2 yet so Idk how co2 work like how heat rises. Any help appreciated +rep for help.

OK so if your light is vented and is sum-what sealed then it should keep your temps to a minimum. i had a 5x5x7 and was running 1000watt with a vented hooded light and temps stayed max 90. make sure your ballast is not in the tent also. co2 is heavier then air so it will fall to the ground so make sure that your source of co2 is above your girls. good luck and KEEP ON GROWIN