Ok, so this would work best if you're only using PC Fans for the exhaust, no cool tubes or anything (which I will be using, along with LED lights) So I'm sitting here planning my next grow box, which will be about 5' high x 2' x 2' - and I'm thinking of how I want to do my carbon scrubber. Then it hit me, I don't know why I didn't think of it before. I'll try to explain this as easy as possible: Ok, imagine a 5' x 2' x 2' box. At the top of this box is a good PC Fan attached to an exhaust hole. Under the pc fan, a couple inches away is a stretched screen or mesh (over the full 2' x 2' footprint). Basically, if you know what a silkscreen looks like, imagine that at 2' x 2' - here's a picture of one So basically, this screen sits below the exhaust fan, and all you would have to do is pour an inch of carbon on top of it. So it's a 1 inch layer of carbon, on top of a screen, with the exhaust pulling air through this. I can't see any reason this wouldn't work just as good as a normal carbon scrubber, as long as all the seams are air-tight and the only possible way of airflow is through the 1" layer of carbon. Does that make sense? It would actually be really easy, if I'm making the box, to have a removable top, where you can fill up the carbon screen. It's so simple, and would only take up an inch of height! What do you guys think of this? I think I'm gonna try it out. This would allow me to utilize much more height in my box. Anyway, I figure the screen, then the exhaust, then a light trap, maybe 6" high at the very top of the box would work great. Has anyone tried this before? Is it too good to be true? What are your thoughts? I will definitely make a DIY thread when I start my box if I go this route!