Question on fans in a stealth box...

Hello all,
I have been spending a lot of time on here reading the past couple of weeks. I have started gathering material for my first indoor grow. I want to make this setup as easy as possible and foolproof as can be. I have a box that is 24 X 16 X 10 that i will be using. Right now I have 3 CFL bulbs for the grow stage and 3 for bloom. I plan on using CO2 and using a CAP controller for regulating the CO2.
My question that has me stumped are the small pancake fans that are used for intake and the exhaust. Should these be running 24/7 or should they be shut off when the plants are getting their CO2 fix. If so, what kind of setup should I be using to turn off these fans off when the CO2 controller is calling for more CO2.

Thanks,
Maxed Out in NC

Hey Maxed Out,

Although I have not started germinating my seeds for my 1st cabinet grow, I have read a couple of Ed Rosenthal's books and I've been reading over these forums for about a month.

For your intake/exhaust: it is advised that you don't use a fan for the intake; you should instead just have a hole that is slightly smaller than the hole for your exhaust fan, called a passive intake. The fan will draw air through the box. If you have a fan on both, and the air going in > the air going out for some reason as the plants grow, it will force a lot of delightful yet unwanted smell out.
For the CO2, you should not run the fan while the CO2 is being administered. This would suck the CO2-rich air out of the box and waste it. Instead, you should hook everything up to the same controller so you don't have to worry after initial setup. You could also use individual timers for each device, set so the fan is off when CO2 is on.

Hope this helps.

Thanks for taking the time to answer my question on the fans. I have acquired a dorm fridge and plan on using a 5" fan for the exhaust on it. Will post photos later in my grow log.

This is probably unwanted advice, but have you considered that your lighting is holding you back much more than CO2? Gt CO2 will give a marginal advantage, but not worrying about it and setting up a modest HPS light for blooming will substantially fatten up your flowers. Even an 80W or 150W light, combined with good airflow, would likely come close to doubling your yield in my experience. I write from having been there.