Easy to Build DIY Carbon Filter

Discussion in 'Indoor Growing' started by MightyBuddha, Feb 25, 2007.


    MightyBuddha Well-Known Member

    I can't take credit for this it has been ripped from another site but it is worthy of posting. I built one about double the length of the one below and found it to be very effective. I also attached it directly to a bathroom fan unit so it is inside of the grow room not hooked to the exhaust.


    Security is important to marijuana growers, and odors can lead the police straight to your grow room. There are a number of 'odor solutions' out there, but they can be quite costly. Here is a simple method you can use to build your own carbon filter. It will take you about half an hour to construct it, and it will cost $20 to $30 dollars.

    Aside from its main advantage of being ultra cheap, this method is also very versatile. It utilizes the exact same activated carbon filters that are used in professional air cleaners, without paying the huge prices. It can be adapted to practically any ventilation system. You do not need any crazy tools to build this - anyone can do it.

    For supplies, everything is easily available at a store like Home Depot. You will need the following:

    1 activated carbon filter - ( found near humidifiers, air, and hepa filters )
    1 small roll of aluminum screen
    1 four inch ventilation end-cap
    1 four inch duct connector piece
    1 roll of duct tape


    No tools are required. A pair of scissors and a measuring tape are all you need.


    The carbon filter I purchased is a 'universal' replacement filter for HoneyWell air purifiers. Since I didn't pay the hefty price for a professional unit, I will cut this to size. It was originally 16" high and about 48" long, so I cut it right down the middle. When the first filter is expired, I will have a replacement ready to go.


    The next step is to cut your aluminum screen to size. I chose aluminum because it will be strong, and will still allow good air-flow. You could substitute chicken mesh or something similar. Since my (cut) carbon filter is 8" high, the aluminum will be cut to 12". The carbon filter will go in the middle 8" of this screen, with 2" coming out of each end to connect to the duct pieces.


    Now we will attach the aluminum screen to the duct pieces, with duct tape. (This might be the first time you have actually used duct tape on ducts!) Do your best to keep it straight as possible.


    It will seem a bit flimsy at the beginning. Continue to wrap the aluminum screen around and around, taping it every few inches. You want it to hold firm.


    After a few wraps it will be fairly sturdy, and able to hold its own weight. However, don't drive your truck over it! Treat her nice and gentle like a Christian schoolgirl.


    The ends of your screen may have little strands of metal poking out, threatening to impale you. Add some more duct tape to cover this up and to finalize the DIY carbon filter. Soon it will be done.


    Now it is time to wrap the activated carbon filter onto our device. Conveniently, the filter I bought came with a couple of velcro straps, so I used them to hold it on. This will be convenient to replace when the activated carbon is expired.


    After she's all sealed up, throw on a bit more duct tape around the edges of the carbon filter, to seal up any gaps. Only tape over the edges, because you want the air to flow as easily as possible. Air does not flow through duct tape. Here is the finished product.


    Time to hook her up to the grow room exhaust! In this case, it is being hooked to a 4" square duct. (That is why I used a 4" round to 4" square connector piece. You may need a different piece to suit your ventilation setup, but a million sizes are available.) Just slide her onto the vent, and tape it down nice and sturdy. Duct tape is your reliable grey friend.


    After she is attached and fire up, things are looking good. It is working nice, hooked to a 60 CFM fan, and you can feel the air flowing out of it lightly. The fan was not slowed down too much, but obviously a carbon filter will add some back-pressure to your vents. I haven't tried this with a slower blower (under 60 CFM), but 60 CFM is not a lot.

    I just hooked this up today, so I don't know how often I will have to replace the carbon filter. The box the filter came in says to replace every two or three months. It does seem to make a difference though. Outside the grow room does not stink like a skunk anymore. There is almost no smell at all, except the faint odor of duct tape adhesive. I'm sure that will go away after a few hours.

    Using this method, everyone can now build their own activated carbon filter. Its quite easy, and you can build it any size you need, to fit any grow room and any type of duct. Could it get any better than that?

    Garden Knowm

    Garden Knowm The Love Doctor

    outstanding buddha.. i will add this to widow makers 101 FAQ!

    420penguin Well-Known Member


    MightyBuddha Well-Known Member

    My bad penguin! I hadn't seen it anywhere (and I confess I did not search very well for it) and was tired of having to link to an outside site. Happy puffin :-D
    StonerSheeb likes this.

    splifman Well-Known Member

    can you add it to the DIY section?
    ablazed blunt

    ablazed blunt Well-Known Member

    very nice. It looks pretty easy to make and it is cheap. Thanks people....

    jondoe69 Active Member

    Very informative. While looking around for info on DIY air scrubbers I stumbled on something about re-using the activated charcoal after a while. I tried it and it is working great on my DIY air scrubber.
    Heat the activated charcoal in an oven for 30 mins. at 350 degrees.
    I know it won't last as long as fresh charcoal, but I was prepared to throw out my old charcoal.....now I'm saving $ and recycling....Sweet!

    Chinga_2_Madre Well-Known Member


    UserFriendly New Member

    Friggin Sweet!

    Chinga_2_Madre Well-Known Member

    The pictures earlier have the scrubber half way built. The thing is a ring within a ring and I used chicken wire (the thick shit) and wrapped it in window screening and a thin sheet of activated carbon to extend the life of the carbon in the scrubber. This SOB works like it won the Olympics. It kicks absolute asss on anything on the market without a doubt. If you need serious odor control, this is the ticket.

    420penguin Well-Known Member

    I will, but I need help. I don't know where that section is at. Sorry!bongsmilie

    420penguin Well-Known Member

    Please help me! I built one from scratch via a guide on planetskunk. But I think that my damn fan is too weak to really make the thing work. I'm still having temp issues and I've got an inline 4" fan that's supposed to push 80CFM. What sort of fan are you running with yours?:cry:
    sub1427 likes this.

    jennyj Active Member

    Thanks for posting this. It looks great.

    I am wondering if the filter could be modified to add activated charcoal - in the screen cylinder?

    Also - do you guys think it would it work ok if it was installed in-line and was vented outside?

    What do you guys think? Thanks again!!

    billybob88 Well-Known Member

    The plans sound great and i am going to tackle this as my next project tommorow. One question. how could i rig it up inline. i know i need it sucking through the filter and the way you have it is blowing through. how would i set it up inline on my canfan?

    moon47usaco Well-Known Member

    Ya i have a question about cfm with this thing... How much will it cut down your cfm effectiveness... Any one built one of these and tested the air flow before and after...

    Also wondering if inverting it and attaching it inside the grow area might affect any thing...

    billybob88 Well-Known Member

    i jsut built a pretty big one. 8 inch diameter and about a foot and a half long. i have it hooked up on my lights that are vented. it goes filter-duct-light1-duct-light2-duct-fan. i have a 270 cfm can fan and havent noticed any real drop in cfms.

    HoLE Well-Known Member

    nice one Mighty Buddah,,I'll be filin this one for myself as well,,thxs

    Keep on Growin


    email468 Well-Known Member

    excellent post!

    1puff2puff3puff Well-Known Member

    That was superb....

    daveg1i Well-Known Member

    very nice set up, thats prob what im gonna build thanks man

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