Im not sure what ure asking zero... but i would always overrate my filter and the difference between intake and outake can be anything from 5-30% i guess so depends on if u have other vents open in the tent..? but if the tent sucks in too much then ure probably straining the fan.
Oh yeah i have known some people,... to turn their fans off at night which causes the humidity to go throught the roof ( not good for mould etc) and when the turn the filters on in the morning the mositure sticks to the carbon and it takes a few minutes before it works well and smells a bit.
If ure planning on being there for a while i would always for for the higher end one from a good brand.. after all its a bit like tyres.. u pay for the mileage u get out of them ,.. cheap ones dont last... etc... and besdies taking one down is hassle for lazy people like me
peace