After I looked at your setup again, I was going to say you are pushing air through your filter, not pulling.

You might want to take a look at some of the FAQs which discuss grow room setup and ventilation. Here's a link to a long FAQ about grow room setup. This link deals with ventilation only, although the entire thread is important and good reading for new inside growers.
http://boards.cannabis.com/indoor-gr...ml#post1634834

Hope this helps. :thumbsup: