# DIY Carbon air and odor filter



## Jason (Oct 14, 2004)

In an effort to please my wife I am taking an idea from our home grow friends. She hates the smell of fruit fly cultures, I mean hates them. Maybe it is a good thing, but she will not even go into the frog room.  

Carbon air filters cost more than $100-$200 just for the filter and another $100+ for the fan. I came across a cheap alternative DIY. Here is where I got the idea.

The ultimate Odour control thread - Marijuana Growing


*Step 1:*

Get the parts.










Since my fan has a diameter of 4" this is what I used, adjust to the size of your fan.

1 - 4" coupling
1 - 4" cap
2 - 4" hose clamps
1 - 6" cap
1 - 6" to 4" reducer
2 - 6" hose clamps
1 - 10' x 3' -- 1/4" hardware cloth/wiring
1 - Box of sheet metal screws
1 - pantyhose, I used the opaque, non sheer.
poly "quilt filler" (from craft store)


*Step 2: *

Assemble the smaller/inside tube first. Use the cap and coupling to make a tube using the hardware cloth. Adjust the length to your needs.










I found it easiest to tie the middle (make sure the hardware cloth is lined up) with some wire temporary then use the hose clamps to install the cap and coupling. I wrapped the whole thing with some steel wire to keep the hardware cloth together. I then put on the pantyhose. On the tube not my legs.  Be careful not to snag them on the hardware cloth. Loosened up the hose clamps and slid the pantyhose under and re-secured them.










The pantyhose will keep the carbon from coming through the hardware cloth.


*Step 3:*

Slide the 4" coupling into the 6" side of the reducer. 



























You will want to put some of the poly quilting batting in here to block any small pieces of carbon from getting through, although it should be a fairly tight fit.

*Step 4:*

Using the reducer and the 6" cap make another tube using the hardware cloth keeping the smaller tube you made inside. You will have to adjust it so the cap from the inside tube will fit snug against the cap of the 6" tube for securement later. 










*Step 5:*

Sorry no pics yet as I have not gotten this far myself. Waiting on carbon. Wrap the outer tube in the pantyhose and then in poly quilting batting. The quilting batting will act as a dust prefilter. 

*Step 6: *

Remove the 6" cap and pour in carbon, shake it down, then pour in more until the 1" gap between the inner and outer tube is full. Replace cap and secure every thing with sheet metal screws. 

*Step 7:*

Install fan so it blows out, sucking in air through the poly then through the carbon. 



















I got this fan from a garage sale for $5. It is normally used for an air duct booster. Although I would bet a computer fan would work just as well.

If done right, you could use this to vent a room and out going air will be scent free. If not you may be drawing in air too fast for the carbon to absorb odors. I will use it to polish off the room allowing the filter to run and continuously clean the air. We will see how well it works this way. 

As far as the carbon, I will be getting mine from Bulk Reef Supply. It is a local company and seems to have the best price.

15 Pounds - 5 Gallons Bulk Lignite Aquarium Carbon - English

I will post more pics when I get it fully set up.

Total cost about $30, not including carbon or the fan.


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## Julio (Oct 8, 2007)

that is great Jason, How long will the carbon last before you have to change it?


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## RPN (Mar 25, 2007)

Awesome post Jason! WOW, thanks for sharing.


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## Jason (Oct 14, 2004)

Julio said:


> that is great Jason, How long will the carbon last before you have to change it?


From what I have read on horticultural websites it should last about a year. I think the quality of the carbon is key to this along with a prefilter. You may find this interesting, keep in mind the data is for aquarium use.


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## edwing206 (Apr 9, 2008)

What the heck were you doing on that website?!


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## ashb (Dec 9, 2009)

So what were you doing on that website where you got the idea from?


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## ashb (Dec 9, 2009)

Oh jeez, we posted the same comment at the same time. Internet-awkward


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## Jason (Oct 14, 2004)

ashb said:


> So what were you doing on that website where you got the idea from?


 Coming up with a solution for a problem. Now in my college years, I would have had a different answer.  Grow rooms are grow rooms, whether it is frogs and bromeliads or medicinal plants. They have a lot of great ideas that can be transfered to our hobby.


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## edwing206 (Apr 9, 2008)

ashb said:


> Oh jeez, we posted the same comment at the same time. Internet-awkward


Hahaha, internet-awkward. That's the first time I heard that.


Jason said:


> Coming up with a solution for a problem. Now in my college years, I would have had a different answer.  Grow rooms are grow rooms, whether it is frogs and bromeliads or medicinal plants. They have a lot of great ideas that can be transfered to our hobby.


Medicinal plants eh? Haha

In all seriousness it looks like a great piece of equipment. If you start posting that your wife messed up your frog tanks we'll know this thing worked, .


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## frogfreak (Mar 4, 2009)

I know what I'm doing next weekend 

Thanks for posting this Jason.


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## swiftfrog (Feb 18, 2010)

with the use of that much carbon wouldn't a filter floss coated in carbon be a cheaper and still effective option? I used to work @ an aquarium specialty shop.


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## Jason (Oct 14, 2004)

swiftfrog said:


> with the use of that much carbon wouldn't a filter floss coated in carbon be a cheaper and still effective option? I used to work @ an aquarium specialty shop.


I doubt that filter floss coated with carbon would even come close to actual carbon. Carbon absorbs odors because it is very porous. A filter fiber coated with carbon "dust" would not have even close to the same amount of surface area.


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## Jason (Oct 14, 2004)

frogfreak said:


> I know what I'm doing next weekend
> 
> Thanks for posting this Jason.


Does it involve sticky icky and a bong?


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## RarePlantBroker (Aug 3, 2008)

Jason, what are you using for FF media? When I started with PDF's I was afraid my wife would say the same thing about the media I was using then. I switche a while back and have been using media from Josh's frogs for 2 years now, and my house smells like Oatmeal cookies on "Fly Day".


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## Jason (Oct 14, 2004)

RarePlantBroker said:


> Jason, what are you using for FF media? When I started with PDF's I was afraid my wife would say the same thing about the media I was using then. I switche a while back and have been using media from Josh's frogs for 2 years now, and my house smells like Oatmeal cookies on "Fly Day".


Potato flakes, brewers yeast, powdered sugar and a little honey mixed with vinegar and water.


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## RPN (Mar 25, 2007)

Jason said:


> Potato flakes, brewers yeast, powdered sugar and a little honey mixed with vinegar and water.



Jason what is powdered sugar? Icing sugar? You ask any bulk store emplyee here for powdered sugar and they try and sell you icing sugar.


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## Jason (Oct 14, 2004)

RPN said:


> Jason what is powdered sugar? Icing sugar? You ask any bulk store emplyee here for powdered sugar and they try and sell you icing sugar.


Yea, same thing.


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## RarePlantBroker (Aug 3, 2008)

That's pretty similar to what I had been using. I think Josh adds some cinnamon to his mix--at least I think that's what gives it that "cookie" smell....

Pretty cool filter though. I may have to build one of those for my workbench in the garage. It should help with the funky resin smells from all of the paint, epoxy, and fiberglass....


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## RPN (Mar 25, 2007)

Off topic of this post but can you PM me your mix ratios?
Ill get back to building my contraption now.


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## Jason (Oct 14, 2004)

RPN said:


> Off topic of this post but can you PM me your mix ratios?
> Ill get back to building my contraption now.


Melos

6 cups potato flakes
1 cup icing/powdered sugar
1/2 cup brewers yeast.
Mix 1/2 cup of dry mixture and add 2/3 cup of 50/50 vinegar/water.


Hydei

8 potato flakes
1 brewers yeast 
1 icing/powdered sugar

Mix 1/2 cup o dry mixture and add 3/4 cup of 25/75 vinegar/water.



RarePlantBroker said:


> That's pretty similar to what I had been using. I think Josh adds some cinnamon to his mix--at least I think that's what gives it that "cookie" smell....


With regards to cinnamon I would check out this thread.

http://www.dendroboard.com/forum/food-feeding/33464-fruit-fly-media-experimentation.html

That being said there are hundreds of people using Josh's mix with no problems that I know of.


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## frogfreak (Mar 4, 2009)

Jason said:


> Does it involve sticky icky and a bong?


It's been awhile, but one never knows.


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## james67 (Jun 28, 2008)

ok, now there are many folks who swear by these diy carbon filters, however........ what most dont understand is that the "real" store bought filter and fan combos move A LOT of air. we're talking fans that generally start at about 150 cfm (for a 4" in system) and with good high pressure. 

the actual filters are another issue as the "real" ones are compacted with a LARGE amount of pressure creating gaps for air in the very low micron range. the result is clean fresh air, even clean enough to be used for some very smelly illegal plants. newer systems incorporate negative ion generation as well but get very costly (not an issue when talking about produce more valuable than gold, but for the poor frog keeper probably out of range)

if you look around you can find good prices on fans and filters, (which should be changed about once every 6-8 months, julio) that are only slightly more expensive than the DIY systems. for fans i suggest S&P td series inline fans as they are very quiet in comparrison to fans with similar CFM ratings. as for filters look around but a 4" X 12" filter should cost about $100

you have to watch out for some of the "great" stoner ideas out there on growing forums, as the hobby growers tend to try and fashion all sorts of crap from household objects, and swear by their results since they havent seen what the "real" equipment can do, due to their inability or unwillingness to buy the correct equipment.

james


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## Jason (Oct 14, 2004)

I agree with a lot of this, but from my research too much air (direct out flow of air) will result in not enough time for the filter (carbon) to absorb the odor. I think a rheostat may be a good idea to figure out what you need if this was your main objective. Using this filter to "polish" the air regardless of fan size will help to remove odor in the room.

I also think that the quality of carbon is the key ingredient. No matter how good the filter looks or sounds cool, if you are using crap carbon you will get crap results.


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## james67 (Jun 28, 2008)

the thing is that the "real" filters are very restrictive, because as i said earlier (at least the good ones) are compacted. the rating of 150 CFM could drop as significantly as 50% with the filter alone. adding sharp bends, restrictive tubing, reducers, etc. will also decrease the airflow so its important to have a fan with a decent amount of flow.

im not doubting that this system will have some effect, but i doubt its ability to stand up to a nice fan / filter combo. 
however i seriously doubt a CPU fan will be able to do anything as they are very weak. the best fan i can find (as far as power is concerned) is delta's model FFB0412SHN which produces an amazing 24 cfm at 13.8V , these are very expensive (about $17 ea) and i still cant see how they could push the air through any filter.
james


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## Jason (Oct 14, 2004)

Gotcha, would you suggest large or small carbon size then?

15 Pounds - 5 Gallons Bulk Lignite Aquarium Carbon - English


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## james67 (Jun 28, 2008)

couldnt tell ya. i havent made a DIY filter personally, but have had some friends that tried them. i would imagine that the finer grains would provide a tighter fit and more surface area available. you could try some DIY compaction but with the store bought filters they claim that its not only the pressing of the charcoal into the filter but the extremely even compaction of the material that creates the optimal filtering abilities.

james


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## RarePlantBroker (Aug 3, 2008)

james67 said:


> however i seriously doubt a CPU fan will be able to do anything as they are very weak. the best fan i can find (as far as power is concerned) is delta's model FFB0412SHN which produces an amazing 24 cfm at 13.8V , these are very expensive (about $17 ea) and i still cant see how they could push the air through any filter.
> james


James, I buy CPU fans from www.newegg.com. I usually by Masscool 80mm fans, they're rated at 31.7 CFM at 12V, and run $1.99 ea. Just in case you need some fans for vent projects....


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## james67 (Jun 28, 2008)

oops! i forgot to mention 40mm. (they are the highest rated 40mm) i only use the 40mm fans since they are easier for me to plumb into tanks because they are much smaller.

thank you for noticing. sorry for the error
james

i should also mention that i get these fans in lots of 10 for drastically reduced price (via ebay)


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