you have a cool tube(or will get one), you already have some of the heat issue whooped. it is known that mj can grow in as little as 30w per square foot, also that most people try for around 50w per sq.ft. for the best results. i try for 40w a happy medium. i dont use co2 but if you do the temps can be a little higher. it will come down to a live and learn thing. you wont want to vent with a co2(unless timed) but that is what the cool tubes do, only suck out heat but not your room air. ok, im no pro i only learned by reading, and this was an article in HT. but im sure you can find the info you need if you study a little bit.