Do intake filters need intake fans?

[ConstantGreen]

My ~100 cubic foot tent has a 170cfm inline exhaust fan with 170cfm phresh filter. I want to add a 140cfm intake filter to reduce dust and debris that the passive intake vents let through. Can the exhaust fan handle the extra resistance? Or would i need an intake fan?

 

[TheFertilizer]

My tent is a 4x4x7 tent, so about 112 CFM and has 6" ducts. I use a 400 CFM fan, and have had it on a fan controller all the way to the Low setting. Even then with any kind of filtration setup on the intake duct (and the passive intakes sealed off) I could notice a visible collapsing of the tent walls. It makes such a negative pressure that unfiltered air rushes in through the seems on the zippers anyway. Then if you don't seal off the passive intakes, then the air inflow just takes the path of less resistance and goes in through there more than the filtered intake. It sounds like you're working with 4" ducting and fans so I would only imagine the problem being worse since the narrower diameter is going to create even more pressure.

I don't know what negative effect it would have on the fans, but you'd end up with less space in the tent for your plants as well as unfiltered air coming in through other places and defeating the purpose.

Another member here recommended to me to pickup a HEPA air cleaner and run that inside of the tent.

 

[Lansky]

I agree with TheFretilizer, you will end up have a tent on the brink of collapse since the air won't flow freely, and you might end up burning sooner or later your fan. I believe the ratio is 20% more on each air filters. So you should probably be safe with a 240 CFM or more air exhaust.