Give this link a look. Hydrosun uses one and says it beats scrubbers by miles. The tests that have been done show very clearly how well the technology works.
http://www.biozonescientific.com/Tiedostot/BZWEB2007.pdf
-Funk
Foothill filters on Ebay has nice filters that are cheap. I tried the DIY route, and it was a waste of time. Ever since I have used the Foothill you can't smell shit.