Wow that does make sense, but it's funny because the lady at the hydro store said that phresh filter recommended that you get a fan that draws more air than the filter is rated for. What do you guys think?
i always match fan and filter or go a little higher on the filter.
291CFM fan pulling through a 200CFM filter will give you uncleaned air NOT GOOD.
A magazine i read in the UK is called URBAN GARDEN MAGAZINE i think its in USA too but every bit of info they suggest on grow room design and ventilation etc always gets tested before publication to make sure that its right.
this is where my calculations have been learned from. they recommend matching filters to fan sizes or a slightly bigger filter CFM .
If you have a bigger fan and smaller filter the filter cant cope with the extra CFM's the fan is pulling which is why filters have CFM ratings too.
Otherwise there would only be 4inch 5inch 6inch 8inch filters etc without CFM ratings .
J