Not sure how many cfm I need for my intake

[bravokillz]

Hey guys, I have a 3x3x6 grow tent and up until recently I've only been using regular desk type fans for my intake and exhaust (one intake and two exhaust fans). It worked well my my last grow but it was very stinky. I have bought a 4 inch 203 cfm inline fan for exhaust with a carbon air filter and i'm assuming that my little office fan won't be enough intake for all the cfm going out. My question is, how much cfm on my intake fan should I have ? I also leave 2 little mesh screens on each side of the tent open, they are maybe a foot wide and 6 inches tall.

Thanks !

 

[bravokillz]

Also I am running a 600w LED with 2 plants under it right now but next grow I will have 3 plants going.