Downshift's Cheapest, Easiest Micro Scrubber on the Net! ~$6 per filter!

This is a carbon filter that mounts on an 80mm exhaust fan commonly used in micro and PC grows. It is about as easy as I have found anywhere and has 100% eliminated the odor coming from my box! (update: only for a couple of days, as it is already starting to smell again... jd4083 was absolutely correct that this is a temporary fix at best. I'm not sure if the filters started to wear out really fast or if my plant just started stinking a lot more in the last couple days, but she's smellin up the room again.)

The Problem:

She's startin to smell a little TOO good!



I have my fan positioned in such a way that a traditional carbon filter would be too difficult to connect to it. (At least for someone of my limited engineering abilities) I wanted a small carbon filter inside the box that would easily mount to my 80mm computer fan exhaust.


Then all of a sudden I got an idea!

I needed the following items:

1. A hot glue gun:


2. A box of carbon filters for an air purifier. I got these at Target and they cost around $10. It comes with 4 filter sheets, and I only needed 2 for this filter so I'll have a refill sitting around!



3. Some 3mm Depron foam or some 1/16" balsa wood. I used Depron foam because I had it sitting around. This stuff if used to make micro r/c airplanes out of. You might be able to find it at a hobby shop, but it's probably pretty hard to find if I remember right. So instead, just use 1/16" balsa wood! You can buy this at Michaels or any other craft stores, and it will cost you about $2 for a sheet of it. I wouldn't use anything thicker than about 3/32" as you'll need your filter to be lightweight! (you'll see later )



Make a box:
Glue 4 pieces together with the hot glue gun to make a box. I made mine about three and a half inches square to fit nicely over my fan. (which is about three and a quarter inches across.)

Fill it with filter media:
I chopped the sheets of carbon to just slightly larger than my box. Then, it just stuffed right in there and didn't need to be secured with anything.

I made it 5 layers thick: Two layers on top cut from the first filter sheet, two layers on bottom cut from the second, and a layer of chopped up bits cut up from the scraps of the first two filter sheets.








Attach it to the fan:

here comes the fun part!


Grab your filter and head to the box...




Hold it up to the fan really close....










and...





let go!




Just let go! The suction from the fan just pulls it right up into place and holds it there. You might hear your fan rubbing on the filter, in which case you would have to pull it off and adjust the foam downward until it is no longer rubbing. You might want two fans stacked on top of each other for extra pulling power, that's what I did and it doesn't seem to be cutting down on my airflow too much.

The odor in my bedroom is now 100% gone! The total materials cost $12 and this is enough for two filters! For $6 and about 10 minutes you can have your odor problem completely under control!

 

Yeah it didn't cut it down too much. I think that having two fans on top of each other definitely helps with the back pressure issue.

Well, I'm already in week 7 of the grow, and it stank pretty bad until I put this on, and now the odor is gone entirely.

I understand what you are saying, and this might not work on something stinkier than my Northern Lights, but it is certainly working for me. When I shut the door on my cab I can hear the fans bog down trying to keep up. Isn't this indicative of negative pressure?

Regardless, It's working so far. In the weeks to come we'll see if it can keep up.

 

I'm not sure if this indicates negative pressure either, but it would make sense. My exhaust set up is simply two 80mm exhaust fans mounted in-line with each other, and a passive intake of roughly 100mm square. Running them inline shouldn't increase the CFMs hardly at all, but it should increase the pressure. Even though each fan is only rated at 35 or so CFM, I would argue that Amps are more important when pushing through a filter, and my setup is 1.2 amps at 12v. I have a 120mm fan rated at 50 CFM, and this doesn't blow with nearly as much pressure as these 80mm fans (it runs at 0.3 amps at 12v) The 120mm fan wouldn't be able to suck through these at all even with almost twice the CFM rating.

My cab is quite small at 18"x12"x24" and my plant doesn't even fill that space properly as I switched to flowering a little earlier than I should have. I am also currently growing Northern Lights, which is pretty low odor. I haven't had any odor control yet, and I'm already only a couple weeks out from harvest.

Thanks for keepin me on my toes though hehe

 

Yes sir it is
​

 

I edited the original post because jd4083 was absolutely correct and after only a couple days she's stinkin up the room again. I'm not sure if the filter just wore out really fast, or if she started to smell a lot more in the last couple days, but it's definitely not working like it was when I first installed it. Oh well, it was a cool idea at first

+rep to jd4083 for knowing what he's talkin about!

 

Yup. I'm only about a week or two away from harvest and as long as I let the smell dissipate every day by cracking a window for a while, I think I'll be OK. I'm going to need a better solution for next time though. You have any ideas for a good solution for a micro sized box like this?

It seems like a 4" vortex is a bit overkill. I'd also rather not have it sound like there's a 747 taking off in my closet

 

Thanks for the recommendations guys. I'll definitely have to look into these for my next cab.

 

I made one of these: Bohbo's DIY 4" Carbon Filter <$15

And against all odds it's working great! I'm still using the 2 80mm fans. It's definitely a bit underpowered, but it's been a few days and there is still 0% odor. Also check my journal out in my sig. I just chopped her down yesterday!