Home made carbon filter: yay or nay?

I'm looking for a cheap and easy carbon filter solution, and I think I may have built something that will work.Let me know what you think. As I've never used let alone built a carbon filter, I based this design off of what Ive seen other people build, so I may be way off base or (hopefully) somewhere in the ballpark.

I took a basic duct coupling with a finned circular base (sorry, I don't know the technical or actual terms for these things, but here is a pic): http://i946.photobucket.com/albums/a...y/IMG_3793.jpg

I then took about a foot long piece of tubular ducting, not the flimsy type of the sturdier, more rigid type, that I had laying around and attached that to the coupling. I wrapped the base several times in duct tape, and then wrapped a layer of duct tape around the body to give it some more rigidness. I capped off the end with yet more layers of duct tape. As I ran out of duct tape and can;t pick up more until tomorrow, it's not complete, but you get the idea:
http://i946.photobucket.com/albums/a...y/IMG_3797.jpg
http://i946.photobucket.com/albums/a...y/IMG_3798.jpg

Once I have more duct tape, I plan to give it a few more layers of skin, and a thicker end cap. I'll then stuff a piece of carbon filter (the sheets that you can buy as replacement filters) down towards the end cap (maybe ill stuff a few), and fill the chamber up with activated carbon that I got at walmart. Perhaps I'll layer it....carbon sheet, carbon, carbon sheet, carbon, etc. Anyway, I'll plug it at the base with some more carbon sheeting, and then I'll poke some small holes all around the body (the duct tape skin) which is where the air will escape from once it's filtered. Once it has holes, I'll wrap the body in a layer of carbon filter sheet, and there you have it.
Ok, again: total noob here, never built or used a carbon filter, and I tried to build what I've seen others build from home made designs (more or less). This should attach to my vent which extends outside of a wall.

Will this work?

Ok, I already found a flaw so I thought I'd post it. The star fin crap at the base allows air to escape, so I need to get a coupling that does not have that on there. I saw plenty and will get one tomorrow.
Assuming this setup could work, would it also work if I attached a mesh screen at the end instead of an "end cap", or is the point of the end cap to force the air to circulate through the carbon before it gets toe scape? My ducting is such that I would like to attach the filter to my ducting right before it exits through the exhaust. So, rather than attaching the filter to the end of outtake port like most people, due to its location and tight fit, it would work better for me to attach the ducting that comes from my light to the filter, and then attach the filter to a SMALL piece of ducting which would then go to my exhaust.
Would the filter work just as well if I left the end open with a screen instead of closed? Would the air rush through the carbon too quickly and not be effective if I did that?

I think you will find that, as built, your filter is going to create a significant amount of back-pressure. About all the home-built filters base the design on 2 cylindrical screens, sandwiching the carbon between them, creating a layer only a couple inches thick. This makes for a large surface area, decreasing the air velocity and allowing for more effective filtering. I imagine the air will be mostly trying to escape through maybe 2-3 inches of carbon closest to the inlet with this design, the rest of the carbon won't even make contact with the air your wanting to filter. If you are able to make it work, it will probably lose effectiveness pretty quickly, because of the air not being able to reach all of the carbon and due to the higher velocity of the air through the carbon that it can reach.

Thanks for your input evilcartman. I've read up on the cylindrical method you mention, but no one ever posts detailed pics (at least none that I could find). If I understand the method correctly, I would wrap chicken wire around a carbon sheet, about 4' in diameter. then cover the outer layer with another sheet and attach that to a duct. Id love to see some detailed, laymen''s photos showing how to build one of these.

I think what im confused over is how much surface area is required to have an efffective carbon filter. If air is pushed thorugh a sheet of carbon, is thqt enough to filter it? I'm wondering if a small end cap stuffed with a carbon sheet or two would work. If air just needs to pass through, using a powerful pump, would any air forced theough the carbon be filtered, or is it more complex than that?
Sorry if these questions seem elementary to some; this is the weakest (and last cmoponent) part of my grow room and probably one of the most important tools I'll need, so I'm trying to get it all right before I begin my grow this weekend.
I'm a visually impaired med pot patient and I'll be growing 6 plants in a DWC setup. My space is poretty small....it's about a foot and a half wide, and about 6 feet long. Lighting and equipment are all set up and ready to go, I just need to build a darn carbon filter and I'm stuck :stoned:

Ok, I found a good illustration that helped me to understand the designed mentioned by evilcartman: http://homeharvest.com/homeharvest20...Cutaway200.jpg

I'm wondering if a carbon filter, like the one pictured abaove, attached to the end of my exhaust would remove the odors?

Also, which would be preferred? A carbon filter at the end of the exhaust, or a stand alone in room filter, like this: Surround Air XJ3000C Air Purifier with Activated Carbon Filter

Any opinion on which will be more effective in removing odors?

Thanks!

I'm a bit late to the party but I think you may find this thread interesting as it contains complete instructions (with pictures) on how to make a D.I.Y. carbon filter.

http://boards.cannabis.com/grow-faqs...on-filter.html

Wow, thanks PhatJay!
That's a great resource. I'm also weighing the option of buying something as the options aren't as expensive as I had originally thought.

I'm thinking of getting this: Amazon.com: Organic Air Carbon Filters - 4" flange 516cfm: Home & Garden

If I attached that to the intake of my pump, would that effectively remove the odor? The air flows over my light and then outside.

Alternatively, I was thinking of getting this: Amazon.com: Holmes® HAP726-U True HEPA Allergen Remover for Medium to Large Rooms: Home &…

Would a unit like this mask the smell, or would I still need a filter on my out-vent?

Many thanks for all the great information!

I'd look into ebay and search for " 4" filter fan ". There are plenty of 4" vortex style blowers with soc filters for around 100 bucks or so.

I like the chicken wire idea, but I would put it at the end instead of trying to replicate all the tiny holes found on production filters. Instead maybe you can have the air come through just the end of the filter and this way it would use up all the filter space instead of the alternative as mentioned earlier. I too think that you probably wouldn't be able to get enough holes in the canister along the sides and then find that all the air is being sucking through the same way. Then again, is that really so bad? Like I said though, if you could have all the air coming through at once on the end, then the flow would be more even and you could use more of the filters surface.

Awesome thanks for the suggestions and information.
I think I have settled on a carbon filter that I'll attach to the intake of my blower. I found one on Amazon for 80 bucks (posted the link in this thread somewhere). I like the idea of building my own, but with my crap vision it's easier, long teerm wise, just to buy something already made.
I may also shove some carbon filtering at the end of my exhaust on top of placing a filter on my intake.....why not? I have a very powerful vent blower and a very small space so I'm not worried about the air flow.

Again, thanks everyone for helping this first time grower out; your advice and suggestions may have just saved my future crop.