vent size?

Is there a way to calculate the size needed for an intake vent based on CFM's of the exhaust fans? I have an 8'x2'x8' closet with a fan with a 220 CFM rating. using mylar lined shower curtain and other mylar to seal opening and while its not a problem yet, the curtain sucks in a bit much for when they get taller. no real heat issues. I have an idea of material and placement just need to figure out the size so i dont try multiple times.

Any help?

http://boards.cannabis.com/indoor-gr...-progress.html

about halfway down you will see ventilation stuff.

thank you

Thats what i needed