I have two 6" inline fans running in my box, the $40 types that look like beefed up computer fans. One is drawing in air at the bottom of my box and the other is pushing the hot air out the top of my box which measures 3x3x5 which doesn't really matter for my question. I have the fans set on a timer and the exhaust runs through a carbon filter, however my question is... when i start bloom how do i keep smell from escaping through my intake once the fan is off and air can flow freely out that hole as well?
you need to run negative ventilation ,this is where the exaust sucks more than the inlet if positive ventilation occurs ,where the inlet blows more than the outlet pressurising the box the smell will be blown out all the cracks this may be fixed as easily as turning off the inlet fan
So running the outlet fan 24/7 would be the easiest solution? Also I have ONA outside the box, how well does that stuff work once I start blooming?