I made a activated carbon filter using $40.00 woth of parts from Menards and it works great. I believe I got the plans from this forum. Sure beats spending $150 - $200 on a pre made unit. All you need is an in-line duct fan, Rabbit wire(Fleet Farm), a couple feet of ^" duct, some duct tape, and a replacement carbon filter for a honewell air purifier (Fleet Farm). !/2 hour and it was done and works great. I suspended it from ceiling using strips of bike innertube and you can barely hear it run. DIY is the way to go when you are not wealthy, not to mention the satisfaction you get when saving cash to use in more important areas such as lighting. My plants were starting to give off an incredibly strong(good) aroma but the filter eliminated all of the smell. If you cant find the plans on this forum just google it. I do reccomend using rabbit wire as apposed to screen material as it is more rigid and allows for more air flow.