Does air coming IN to a grow box have to be equal to or less than air flow going out?

Here's my situation , I've got a 3x3 wide by 5.5' tall plywood box, I've got a HydroFarm 265 CFM squirrel cage that I might use for IN FLOW , and I have a Can Fan 9000 filter connected to a Can Fan Hi Output 5" inline fan to take out smell. With the CanFan Filter connected to the CanFan the OUT-FLOW is only 109 CFM.

So this means the air pressure going IN is greater than the air going out. This is making me think that the air pressure inside the box will be so great it will leak out around the rubber seals around the door as well as leaking the smell.

I'm wanting to forget about using the 265 CFM squirrel cage and downsize to a Soler and Palau TD-100 4" inline fan because the IN-FLOW would only be 97 CFM which would be less than the 109 CFM going out, so the chance of smell leaking would be minimal if not non-existent. I want to add that this Soler and Palau fan is only $69.60 and $82.00 with shipping.

I only want to have 1 in-vent and 1-out-vent , and I'm running a 6" Oscillating fan on the inside upper wall of the box. My light is a 400 HPS and my main concern is SMELL , I live in the mountains of Colorado and its already getting cool.

Is this right concerning smell and the OUT-FLOW having to be equal or greater than the IN-FLOW?

you should just use passive air intake , no fan or blower blowing in,
just the one inline fan pulling the air out

I agree with sniffer. You are going to want to have your fan hooked up as exhaust only. The suction created by the exhausting fan will great back pressure and cause fresh air to come in through your intake ports. This gives the air inside your grow chamber a nice path to follow--- i.e. fresh air comes in and hot dirty air has a clear path out.

they are correct that pressure pull u were talking about ca \nwork in your favor with your best fan as an exaust
and always check your humidity lol
ph and double read your nutrition bottle
all the advice a fellow grower can give
well i hope it gos well
and plenty of light well heres hoping your batch will get u stoned