Design Requirement for a Scrubber?

How dense is activated carbon? I've seen so many plans on this sight for build-your-own scrubbers but most of them are designed with a cylinder- store bought desighn in mind (a few inches of carbon surrounding an empty tube from which the in-line pulls through). Problem one, not very much carbon is in contact with the smelly air and two, if that is the case, not very space effecient. Would it be possible to just pull air through two feet of PVC pipe filled completely with carbon or would that be too much friction/drag for my 175cfm elecient in-line to handle.

the key to the surface area is in the "activated" part of the carbon. It is very pourus.. I think trying to pull air thru 2 feet of activated carbon would be like trying to shoot a deer with a scud missle. Way overkill.. you probably only need an inch or two of activated carbon to remove 99.99% and it will work untill the carbon is spent. just my 2c

Why are there so many cylinder designs? It would be so much easier to fill a container with activated carbon, screen off both sides, to keep it all in and you're done. I feel like I missing something.

maximum surface area for the minimum amount of volume displaced. I know you are seeing it as an easy alternative to an expensive metal can.. I guess its not a bad idea but most people i talk to get the can sooner or later and have no regrets when they do

Lets say I have a good exhaust fan in my grow room, which I pipe to the outside of the grow room in say, 4 or 6 inch PVC, and I add a 5 gallon bucket with a lid, and full of charcoal inline with the PVC piping. Would that get rid of the smell so nosy neighbors couldnt catch a whiff? Would one pass through the bucket do the trick? I would be exhausting to the outdoors, so as long as it got rid of the majority of the smell i'd be happy, as nobody would be coming close to the exhaust. It would be going out a high roof.

The only thing i am concerned about is if the fan can push air thru that much charcoal.. the metal can filters only have like an inch or two of carbon to pull air thru.

I work in the HVAC trade and I come across some pretty strong inline fans. 6", 7", 8". Heres the brand we use. http://www.rewci.com/fadl408cfm8d.html
Hell I could probably even rig that box that comes with it into something for the charcoal. ;) With a homebrew scrubber though, the fan is going to be the most expensive part of it, and there has to be a quiet and powerful enough fan out there.

I drew up an idea I had here: http://img143.imageshack.us/img143/4672/scrubber5zz.gif

With my situation, i'm really not concerned withmy grow room itself smelling inside. My biggest concern is that people outside passing by, like the mailman or a neighbor doesnt smell it. But, I think this same thing would work if I wanted to use it IN the grow room itself to cleanse the air from the source. I am just trying to keep the electricity consumption down, so it would be one less fan motor running if I tie it into my exhaust.

Heres a quick link I found to the bucket trays, but i've seen ones that are more shallow then these: http://www.amazon.com/gp/product/B00...lance&n=228013

i think it will work fine for that. I took a look at the info. And the way I would look at it.. worse come to worse.. if it doesnt work you already set up all the lines and routing to slap a premade filter in its place and you can reuse the activated carbon in the metal filter so the most you are out is the 5 gal bucket and lid setup if it doesnt work.. all the other tubing and fan and stuff you can still use for the real filter.. Id go for it.

and let us know how it works if you do!

and if it matters i was an industrial mechanic for 6 years so.. i kinda have a decent idea about improvising :)

oh and i would reccomend using activated charcoal.. instead of regular charcoal but only if regular charcoal doesnt give the desired result.