the homemade scrubbers only uses carbon prefilter pads and would be Useless for flowering.
I have always heard that a can filter should be sucked through and never blown out of, this is why they have prefilters on the outside.
One of the reasons I would prefer to suck through the filter is ducting. If you got your fan hooked up strait to the filter like you should, any of the ducting that is going outside your grow room is pressurized with clean air. If you had your filter hanging outside there is more chances that the smell could leak out through the ducting, or any connections, even the fan.
If you suck through the filter all your ducting is getting pressurized with clean fresh air, even the inside of the filter is getting filled with clean air.
If your blowing your exhaust out to the filter you are pressurizing your fan, your ducting, and your filter with odor, so theres more chances for leaks and error. I would imagine you would have to use more ducting to blow through the filter, where as if you intake through a filter you can eliminate most of the ducting.
This is just my opinion, great thread, I would love to hear more.
Thanks