has anyone a rough guide to getting the correct carbon filter size for 'x' amount of plants?

ie i had 8 on last grow and 5 on this one with a total of 7-8month growing for the 2 grows. i have a 5" carbon filter from greens and im due to harvest within the next week and i can smell my green out side when the light is on (venting outtake air through floor boards so can smell them through ait brick in my back yard)

so would you say its safe to say a 5" cf will do 1 grow (3-4month) of 10 plants, and to change the carbon pellets or the whole filter every grow so the is no risk of gettingh sust?

so for example say you had 60 plants growing would you use 6x5" cf's or an equivilant ie 3x10" cf's?

my next grow will be in a loft and outtake through chimely so there will be less chance of smelling it at that hight, but still id rather vent out very little smell all the same