Carbon Filtering - Freestanding Filtering Unit?

Hey guys, have an idea I'd like to run across you. I'm growing out of a small room and don't have anything fancy set up. (And can't afford it ATM.) Just a room and some CFL's. Now I know carbon is the way to go, but since I don't have ventilation set up or in a cabinet, I am wondering if there is a product that would work similar to the ONA Breeze fan unit. My thinking is if I could have a small unit like a fan on top of a bucket pulling air into some sort of carbon, would that work? Sort of filtering the whole room at once over and over again. Air would keep being pulled in and sent back out through to bottom filtered. Is this crazy or might potentially work?

Google is my friend: http://www.instructables.com/id/Activated-Carbon-Air-Filter/

Or would this work for such a small grow? We're talking 2-3 plants MAX. http://www.bionaire.com/Product.aspx?cid=46&pid=197&search=FpZLOn0LyeEqLvcNOjUPEw==

Learning2Hydro said:

Google is my friend: http://www.instructables.com/id/Activated-Carbon-Air-Filter/

Click to expand...

I made a room air purifier that's pretty similar to the one in the link...except that I used a Stanley blower fan and HEPA furnace filters rather than carbon filters (since I wanted to remove allergens, not odors). I don't see any reason why you couldn't mount a carbon filter like this (http://www.amazon.com/HBH-Enterprises-Carbon-Filter-10x18in/dp/B0002DH3DC/ref=sr_1_12?ie=UTF8&qid=1304022002&sr=8-12) in there instead. This particular unit is sealed up with tape on the top atm, but if you're interested, I could open it up and take some pics. It's basically two 10" x 14" HEPA filters (I cut a 20" x 24" furnace filter in half)...one on each side (right behind the vent covers in the pics) with the blower inside. The blower sucks air in through the vents/filters, and blows it out the front. I attached some brackets on the inside to hold the filters in place...and they slide right out when it's time to replace.

I have a cloth over top of the exhaust vent in a few pics that may give you an idea as to how much air blows through this unit. I usually keep the cloth in place as shown to prevent papers and whatnot from blowing all around the room...it's that powerful.

The problem with trying to purify the air in an entire room using a box equipped with a pc fan is that you're probably talking about a large volume. If your room is, say, 10' long x 10' wide x 8' high, that's 800 cubic feet that you need to filter...so a typical (or even heavy duty) pc fan is unlikely to be powerful enough to do the job efficiently (and without a lot of noise), The Stanley blower is relatively quiet, and blows A LOT of air. In the box I constructed, it runs pretty much on high speed (it's adjustable, but revs up automatically to high speed due to the resistance of the filters), and I would guess (from the specs, and what I've read) that it's pulling roughly about 200 cfm (just a guess...I really don't know the exact number). Granted, a carbon filter may slow that down a bit...or not. I never tried one. But I think it would still be better than any pc fan (and I did try a number of the more powerful 120mm pc fans in a similar build...they're much noisier, and not nearly as good at pulling through a filter, imo).

The whole build cost me just under $100 (inluding the HEPA filter, which cost around 20 bucks, I think)...with a carbon filter it may be a little cheaper.

I was considering the PC fan deal until you said that. My thought was to build a rectangular box and mount two intake fans and two exhaust fans to push air through. Your idea sounds more efficient though. Thanks for the great post! Was it difficult at all to do?

Also, I like your style. I can see building a decent looking wood box to hold the blower, then routing the air the same way you did. Instead of a charcoal filter, I am thinking using a filter (cut like yours) and building two little trays if you will to fill with activated charcoal. I'm thinking I will need to put some brackets in and using that to support the filter and then filling the space in between with charcoal. I could even use a HEPA filter as well and accomplish both, no? Would be some healthy air in that room!

Took about two hours maybe...I spent some extra time painting the vent covers and whatnot, just to make it look a little more acceptable since it was sitting out in my office for all to see. The cardboard box was just supposed to be just a prototype (planned to eventually build with plywood), but it worked well and I liked the ghetto look of it, so I just kept using it as is. Bought a few larger moving boxes at Home Depot for building a larger unit that would use two full-sized furnace filters, but never really felt the need to change it. For a smallish-sized room, I think it probably does a decent job of exchanging the room air. As a bonus, the cardboard is super easy to work with (cutting the vent holes, etc), so really only needed a boxcutter, a drill, and a hacksaw (to cut the aluminum brackets that form the "filter slots" inside). Would have taken probably twice the time to make it out of wood, I'm guessing.

I tested three different 120mm pc fans (rated for high airflow rates, around 130-200 cfm) installed in another cardboard box. The airflow was decent using just a paper towel as filter, but I never tested it with a HEPA or carbon filter attached. I'm pretty sure it wouldn't have worked well...and they were fairly loud when running at least two at the same time. The Stanley blower is a MUCH better alternative, imo...and only costs about 50 bucks. It's a really useful fan. I bought an extra just to have for future use...they can be easily modified to connect into 6" ducting and used as exhaust fans for air-cooled lights or even whole cabs with carbon scrubbers attached. You can even use 'em to dry off wet carpets and floors, lol.

Yeah, my concer with the PC fans was that they wouldn't be strong enough. You basically already tested it out for me. I think I will do one with wood since I am already going to have to buy a circular saw to build my stealth dresser. Just will have to plan out how to place and hold the charcoal. You also just metioned the other thing I was thinking. I thought I could hook it up to the dresser when I get it finished without having to worry about additional fans, filters and tubing. Could just place it on top or beside the dresser. Of course, it wouldn't be super stealthy then. But it would work as a step between until I want to internally filter the cabinet. Nice thinking.