Carbon Scrubber Step-by-step

This is a step-by-step redo of a 6 inch, 250 CFM carbon scrubber that I originally posted in the General Indoor Growing forum. I'm definitely not on par with Rumpleforeskin, but was inspired by his excellent step-by-step tutorials to do a better job.

Based on comments in the original thread, there seemed to be enough interest level to warrant a clear and illustrated instruction set.

So let's go!


Parts list:

1 - Pet odor control filter ($10 at Walmart, Home Depot, Lowes)
1 - 6” In-Line Duct Fan ($30 at Home Depot)
2 - 6” Duct Flanges ($4 each at Home Depot)
1 – Roll of 1/2 inch mesh hardware cloth
3 – Wire nuts
1 – Power cord (PC power cord or grounded extension cord)
8 – 4” Nylon ties
15 – 8” Nylon ties
2 or 4 – Wire coat hangers (2 extra required for optional hangers)
1 – 6” Margarine tub lid
A roll of foil ducting tape





Tools needed:

Drill with 5/64 inch bit
#2 Phillips screw driver or drill bit
Scissors
Hammer
Center punch (or just a sharp nail)
Pliers
Needle nose pliers
Wire cutters
Wire strippers




Step 1:

If required, assemble the two flanges by simply inserting the tongue into the groove.




Step 2:

Using the wire cutters, cut a piece of wire mesh to 21 ½ inches x 20 inches. Don't bother flattening it out since you will need to form a tube anyway. For custom sizes or to maximize the use of the filter material, see the notes at the end of this post before proceeding.

Form the tube around the end of one of the flanges. Use a 4” nylon tie to hold it in place as shown (note that I have the flange backasswards in this photo as an example of what not to do):




Step 3:

Work your way down and put another 4” nylon tie in every 5th hole. Don't snug these all the way down yet.




Step 4:

Now insert the other flange in the opposite end and then snug down all of the nylon ties as tight as possible. Cut off the excess from the ties and roll then down so that the bulky part is on the inside of the mesh tube.






Step 5:

Cut the hanger part off of two coat hangers. Then use the pliers to straighten the two pieces. For the 20 inch filter, you will cut these down to an initial length of 23 inches.






Step 6:

Use the needle nose pliers to bend about a half inch on one end of one of the wires at a 90 degree angle. Then put this end in one of the holes in one of the flanges and determine exactly where the bend on the other end needs to be, as shown. Then make another 90 degree bend on that end.



Use the first wire to make a duplicate with the other coat hanger wire. Cut the end parts to where each of the four ends are 1/2 inch long, or a little shorter.




Step 7:

Now install these wires on the inside of the assembly, poking the bent ends out through the holes in the flanges. Note that you may have to rotate one of the flanges to align these holes so that the two flanges line up.



Use the needle nose pliers to complete the bends on the wires to 180 degrees, as shown. Do this with both wires on both sides of the assembly.




Step 8:

Now for the air sealing & light proofing. Cut a square of foil tape to cover each of the four holes where the wire ends are, as shown.




Step 9:

Use the foil tape on the inside of the flanges to seal the gap created by the stamped flange. To greatly reduce the frustration level of this step, use 5 or 6 inch lengths of the tape to go around a little at a time. Only pull back about an inch of the backing and then use the part of the tape that still has the backing to position it where you want it to go. Then press down so that the exposed part of the tape gets secured in place. Now just pull off the rest of the backing as you press down the tape so it goes exactly where intended.



Once you get around the entire inside circumference, also cut and place a strip to cover the crack of the tongue and groove that holds the flange together.




Step 10:

Cover the outside of the margarine tub lid with 4 strips of foil tape about 6 inches long and then trim away the excess with scissors.







Step 11:

Tape the lid to one end of the scrubber assembly. First use three or four small pieces of the foil tape to hold the lid in place. Then cut a length of tape long enough to go around the entire lid (approx. 19 inches). Complete the taping as shown.








Step 12:

OK. Time to put on the filter material. First put three of the 8 “ nylon ties together as shown. Don't put more of one tie into the next tie than you have to or it won't be long enough to go around the filter. Make four of these 3-tie assemblies.



Open the carbon filter package. Discard the plastic mesh plate and hardware bag, we don't use those. Wrap the black material tightly as possible around your filter and use a small piece of foil tape to hold it in place.



Now wrap the green filter material around that and use one of the 3-tie assemblies to hold it on. Put this one at around one third of the way in, as shown. Don't snug it down all the way as we'll want to pretty them up once all four have been put on.



Once you get all four put on, you can move them around and pull on the filter material some to make it all nice and pretty and then snug all of the nylon ties down for good.



Snip off all of the nylon tie ends, and now you have completed the filter portion of your scrubber!




Step 13:

Now we'll be attaching the fan motor. For this, we'll need the fan motor, the power cord, the three wire nuts, 3 more 8” nylon ties and one more 4” nylon tie (not shown).



Slide the motor onto the scrubber assembly, with the airflow arrow pointing at the scrubber (as shown in the following picture). Use your center punch and hammer to make a starting dent for your drill. Be sure to place this where the screw on the inside does not come in contact with the fan blades! Drill and then use one of the sheet metal screws that came with the fan to attach the fan to the scrubber. Repeat on the opposite side with another screw.



Cut the female end off of your power cord (if there is one), strip back about an inch of the outer sheathing, and then strip about 3/8 of an inch of off each of the three wires. Use the wire nuts to connect green to green, white to white and black to black. If your cord has blue and brown instead of white and black, connect blue to white and brown to black.

For strain relief, use a small 4” nylon tie to strap the fan wires to the power cord. Then use another 3-tie assembly of 8” nylon ties to strap the power cord to the fan body.




Step 14:

Your fan/scrubber assembly is almost complete now, except for the protective screen for the fan blades. Cut another piece of the hardware cloth to 8” by 6”. Then use the edge of a table to bend one inch of each end of the 8” length to 90 degrees, as shown. Use two more of the sheet metal screws that came with the fan to attach the screen to the fan body. To minimize snagging, use your needle nose pliers to curl in each of the four corners.






Step 15:

You can hang your scrubber however you see fit. One way is to use two more coat hangers. Cut and straighten as before. Then with the needle nose pliers, bend a small loop at one end. Wrap the wire around one of the flanges and insert it into the loop. Pull it as tight as you can, just like a nylon tie, and then bend it up to hold it there. Next bend another loop in the other end of the wire to hang it from. Repeat this on the other flange with the second coat hanger wire, and voila, you are done!





The completed carbon scrubber - with hangers!




Notes on custom sizes:

You can make your scrubber any length up to 25 inches, which is the length of the filter material, rather than the width as the step-by-step uses. However, any length over 20 inches will require that you wrap the 20 inch width around your scrubber, which is not quite long enough. In that case, you can use the foil tape to block-out the portion of the scrubber screen that ends up uncovered. By making your scrubber 25 inches long, you maximize the use of the filter material by using all of it, rather than having some overlap.




In closing:

After you have all the tools and materials, it should only take about an hour from start to finish. After 2 to 3 months of usage, you can simply replace the filter material. You can re-extend the 3-nylon-tie pieces by adding another tie, so a filter replacement only requires 4 more 8" nylon ties.


You can hang one or more of these scrubbers in your grow area to clean the air in the room through circulation alone and/or use one as part of your exhaust flow.


Keep it green and smelling clean!

 

Thanks guys.

I have a few of these and the noise level seems to vary. Possibly, these fans are inconsistent in that way. I haven't tried anything to noise-proof them because it's not really a problem for me. I have one of those remote switches that controls my main intake and exhause fans, so if I were to want to kill the noise, I just switch them off from upstairs. I would not consider them quiet enough for real stealth purposes, but I'm betting that could be worked around.

I found the manufacturer's web site and they claim 250 CFM, which is probabaly overstated. Still, the air flow seems strong even with the filter. When I just had one of these pulling air out of the 12/12 room and before I added a 4" intake fan, I could see it raise the flaps on my intake cover when I switched the fan on. I have no real way to measure this.

 

Hey Johnny!

Here's the theory: The air should be pulled into the filter by the fan and blown out through the filter material. The reason for this is that when the air fills the filter, it creates an even back pressure and then uses all the filter body to pass air back out. If you pull air in through the filter and out the fan hole, it tends to come into the filter at the point of highest suction, which is up front near to the fan, and so you don't use all the filter material.

That's the theory, but I have two of these filters free-hanging in my 12/12 room that go backwards from that. I did that because I was trying to direct the air to get a desired air flow pattern. I've had those filter skins on too long, although they're still doing the job. The accumulated dust makes it easy to see that the filter material is actually being used quite evenly. So I'd say, it doesn't really matter which way you go!

New Xbox guy! Sup?!

If you check my grows, you'd see I have quite a few plants and always a few in various stages of flower. Many different strains. People come over all the time and no one has ever suspected anything nor mentioned the odor. Of course, we always have some pretty dank weed around and every one knows that, so who'd suspect a touch of dankness in the air? I'm sure that helps, but yes, these filters are effective - however, you'll need enough to handle your setup.

I use two free-hanging in the 12/12 room, one that the 12/12 room vents out of, one free-hanging in the veg room and one that the veg room vents out of. So 5 for my op. I'm totally happy with what I have for odor control, but it is not 100%. If LEO was on the way, I could turn off my exhaust vent fans and there would be no smell at all.

Hope that helps you decide! Good luck with your setup, bro!

 

Yes, that is correct. Be careful, but it should work. Since the thermostat isn't in your closet, you can't assume the closet will stay at 72, so whether or not you'll be able to maintain your temps is still unknown. With lights, the closet will probably stay above that. If you're going LED, you'll probably be well within range. You might even end up putting a timer on your exhaust fan to maintain around 78/80 degrees.

 

Nice job on the cab, Xbox! Yeh, please do post your results here if you try the scrubber. It would be great if a few people did that. And thanks for the rep, dude!

 

Hey JB, check your new thread for my response.

 

Hey XBox. No, I haven't tried anything else. In my house, there are times that you can smell a hint of skunky odor, but it's very insignificant and easily covered by the fact that we smoke a lot of pot. So these filters are a very effective approach for my situation.

My areas that use the 5 filters add up to around 1100 cubic feet. I would think just one in a small cab like yours would do pretty well.

 

Thanks for the props, WGH!

The other filter would do a better job for sure with that activated charcoal fill. I think it would probably achieve close to 100% cover-up while the charcoal was fresh. The trade-offs are exactly as you mention. I believe that the design I provided would be quite adequate for your small space. Since your space is so small, you could even get away with doubling the filter material if you found that some smells were getting out - but I doubt you'd need to.

Good luck with your grow, bro!