Inline Carbon Filter under $40


Well-Known Member
This is a very easy and inexpensive build from items found at America's largest department store and home improvement store. From the department store, you'll need to get the following item for less than $7

and this for about $10

From the home improvement store you'll need to get one of these 4" 90° PVC Elbow (Hub x Hub) for less than $5;

and 2 of these 4" PVC grates for about $3 each

From either of those stores you'll also need to get a roll of duct tape. Also, you will want to find a small mesh bag,

but a length of panty hose will probably work. I bought 20 lbs of activated carbon on ZEEbay and it came with a small zippable mesh bag that worked perfectly.

What I did was filled the mesh bag up with activated carbon, (roughly 90% full). Then I cut 2 of the black foam carbon prefilters to fit into each grate. I then took one of the PVC grates (with a prefilter in it) and put it into one of the ends of the elbow and duct taped it into the elbow. Just wrapped a length of duct tape around the circumference and folded it over as depicted below.

I then put the mesh bag filled with carbon into the center of the elbow and worked it around so that the carbon was not rock tight anywhere in the elbow, but still covered all available passage ways to the other end. the key is to get your air to flow through the carbon gauntlet. If there are any spaces along the way, they will give almost no resistance and the air will flow to the point of least resistance and stink your house out.

Once you feel that you filled the elbow evenly with the mesh load of carbon, then put the other prefiltered grate into the elbow and tape it the same as you did on the other end.

For my space, this is a great way to tap into my cabinet at a high point to expel filtered heated air. This also serves as a light block and no light leaks out this way.
Because this is an inline filter, you can fit it into your duct work anywhere. You can swap out the elbow with any other shape of 4" PVC, so long as both ends are flared out to receive the 4" grates.

Hope this gets the dank out of your home.:peace2:
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