Although the actual filters themselves work equally well either drawing air though them or forcing air through them there is a practical difference in the latter, particularly if the filter and fan are outside the grow area. If there any air leaks in the section between the fan and filter in a "fan push through filter" system dank smells will leak out, nullifying all the work and expense. If you have any leaks in as "fan intakes through filter" system you might have slightly less effeciency due to the leak, but absolutely no odor leaks.


My :twocents:,
M.P.