PC Grow Box Question.

Hey all,

Question.
I'm preparing for my first PC grow, and I was wondering do I need two fans to make things work properly for intake/exhaust?

And if so, do I need to install one of the fans backwards so it will blow air into the case?

i got by fine(temp wise) with one fan
but then i only used 1 27w bulb(which also worked fine)
the small pots didn't work out for me, changed back to a larger setup