grow rooms intake and exhaust.

So i was just wanting to know if its normal for the grow room (made by wood frame and 'panda plastic' 90'' H, 90'' L 52'' W ) The fan with cover 165 cfm, and i have 4 intake vent 2 with small cheap fans blowing in but its still sucking the walls in a fair bit, is it normal for it? i just dont want to burn the fan out, worst comes to worst i buy a fan controller??

I'm going to be dealing with the same thing, my grow box is 6 1/2'x4'x2' made with 2x2's and 6ml black/white polly, I'll be using a 6" 430CFM inline fan so if I don't make the intake vent big enough it could very well suck the sides right in on its self, lol. The guys at my local hydro shop said that its very common for the sides of tents or grow boxes to suck in a little, however if its sucking in too much then make the intake vent a little bigger, you could get a fan controller but don't turn it down below 70% or it will wear down the fan motor, hope this helps.