Grow box design, need help on intake vent?

[WESTCRAZY1]

So after doing a lot of thinking and spending countless hours researching online i have made up my mind on the size of my grow cabinet. The measurements are 4ft tall, 2ft wide, 2ft deep. I'll be using a 250w hps cooltube in there. Im planning on running 6-8 plants in there using 5" square pots, depending on the grow space it may vary but so far this is how many plants i want. For ventilation im planning on cutting out a 6" port for the exhaust and 2, 6" vent for passive intake on the bottom. The exhaust will be air out using a 6" inline fan with a carbon scrubber/filter along with a speed control set to the lowest setting (dont wanna attract any unwanted attention). For the intake i'll be installing a 6" dark louver vent on there. My question is, will the 2, 6" passive vent intake be enough to match the 6" exhaust for a stable air movement? Or would i be better off just cutting out 1, 8x8 vent for the passive intake? I went ahead and did a sorry job at sketching out my grow box plan using paint on my computer and i've attach it along with this post. Please point out anything that can be improved on or any suggestions. Thanks.

 

[ScrogFrog]

Your plans sound good to me man. I used that 2 intake, 1 outtake method on one of my grow cabinets, those intake fans will create good air flow through your grow box, temps should remain ideal seeing that you r air cooling your light. I think even without cooling the light your box should be at a reasonable temp, but if it gets a lil high u still have room to add another exhaust.

 

[Thebogie]

Vent

I am building about the same size. Plan on a 6" fan with 3 6" intakes. How are you filtering intakes?
Thx