Does a carbon filter go inside or outside of the tent?

dst you got i have never seen so many right people in my life and none are the same.
i am a new just wondering if a certain size is best. my grow room is 2x2x4 and have no choice but a push threw.
i will have 2 120 mm fans for intake and 2 for exhaust.
do i want any pressure difference i would think maybe slightly negative so it pushes through without leaking

PSUAGRO. said:

In every type of filtration (house/hvac/purification systems) the blower/fan is always after(pulled through) the filter.........Without question you keep the filter in the tent, unless it's not possible due to inefficient(flawed) grow room design........good luck

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Hi DST.
My self built grow room is flawed. Not enough room to put a filter inside. need to somehow push air through a filter outside the grow room to purify air/odor. Any ideas?
Thanks,
Eggy