It's a tent, it's going to have leaks. The key is to make sure it has negative pressure.
Randall, the 4" fan may not be strong enough for the filter. Figure your volume (112 sf), you should be blowing that volume of air out a few times every minute, meaning a CFM rating of about 400, AFTER you have taken into account the drop from the filter and any bends in the hose. How big is your intake?