I'm sorry man, but I'm just not able to be quiet today. I'm going to quote straight out of the Medical Grow Bible (cervantes) here about setting up ventilation.

"(when using active intake) The ratio of 1:4, ie; 100 cfm intake fan, 400 cfm exhaust, should give the space a little negative pressure"

I know that negative pressure in your space is good, and positive is bad. If you have any positive pressure in the space, it will blow unwanted odors out through any crack in the space. If you have negative pressure, you are always containing your affected air, thus giving you the option to run it through a scrubber before expelling it.

I know this is for a smaller CFL grow, but the principles remain the same. Sorry again, but I still love you Shake.