Howdy peeps, I'm going to put a little blurb in here about the ventilation I've got going on here. I had a guy think I was crazy for venting the hot air out of my tents instead of pulling air through from outside. It is vital that the air you vent is pulled from inside the tent its self via carbon filter, unless you want your entire house to smell like Otto's jacket.
Now keep in mind that I do not use C02 (this allows higher temps, therefore timed/less venting).
Here's what I do, as you can see I use a huge can filter with 82lbs of activated charcoal in it as my intake (inside the tent, mine is on the ground but higher in the room is even better) . From there it is attached to my 2 cool tubes( each with a 1000watt light inside) by 8inch ducting. From there it goes up to my 8inch inline fan (which expells all the air in my room @ every 4or5 minutes) and on up through a hole in the top of the tent. From there the ducting runs to an exhaust port on the side of my house.
Now this is important.....make damn sure that there are no leaks in any of your ducting or where it attaches to the cool tubes or fan or anywhere else. Any air that gets in from anywhere but through your can filter is gonna smell like weed and then the gig is up, so always check.
Now you have achieved negative pressure in your tent, air is constantly coming in through your vent flaps (hopefully located at the bottom of your tent) so it is impossible for smell to escape the room. I have these set up in nice cool basements, and it gets fucking hot where I live in the summer...its a desert....and I don't run any A/C. My room peaks at 29-30 celcius in the peak of the summer heat, winter time I run a little heater at night...thats it thats all, I hope its been helpful.