Carbon scrubber (theory)

[I<3weed]

Ok, finally got my email w/ my password so i can finally post!!! I've been on here for months reading up on everything, and now i can finally ask some specific questions. Ok, heres something i've been thinking about lately. I dont know much about airflow, but this is how i figure it would work. On the traditional scrubber, u have a tube with a thin layer of carbon around it. When it pulls air, wouldnt it just pull air from the closest point to the air exhaust? I mean "path of least resistance" would play into this wouldnt it?
So i figured, what if u just took a solid tub and filled it entirely with carbon. The air would be forced through carbon a foot thick, instead of a thin layer. I drew a doodle to kinda help u get the idea.
So does anybody think im onto something or am i a retard?

 

[POTential]

It's a symbiotic relationship. If you add more carbon it increases the scrubbing/cleaning effect but you lose "airflow" which is a decrease in your cfm. By using less carbon you increase the airflow by upping your cfm but less carbon is available to clean the air.

I built my own scrubber some time ago and I am amazed as to how efficiently the activated carbon works. I thought I would be changing the carbon on a bi-weekly basis and I haven't had to change it in months!

It also depends on what type of carbon you use. They make carbon pellets which definitely helps with the airflow but isn't as effective as the "fish-food" style carbon.

 

[Weed420]

For small grows it doesn't take much and you can use anything.5 gallon bucket,drill a bunch of holes.put the carbon in a pair of old nylons,drill a 6" hole in the lid attach a 6" tube and hookup your 6" flex hose to the motor. 5 gallons is way to big for your size but even a coffee can will work.

 

[I<3weed]

I was thinking of making something like this, using pvc. I like the bucket idea, that hadnt even crossed my mind.

I figured this way the scrubber would have way more surface area to collect odors. Yeah, its gonna take more carbon to fill it, but i figured it be worth it.

 

[I<3weed]

Oh, the pipe w/ the carbon in it, I figured is gonna be a foot long, the diameter is 4".

Im gonna run a 72cfm fan on it, how much do u think this is gonna restrict it?

 

[POTential]

With the whole center filled with carbon you may be disappointed with the airflow. That 72cfm is gonna drop drastically. Check out this thread, my homemade filter is at the very end. I just noticed that Moose asked me to post a tutorial on this so If you have any questions I just might break down and do so.

 

[I<3weed]

I read the post, the scrubber looks nice. How much did the 85 cfm fan "feel" restricted? Did u loose around 1/2 ur flow? My cabinet is 35 cu ft, so i figured if it cut my flow by 1/4, i'd still circulate the air around once every 2 minutes. (im running a cool tube)

I read about the activated carbon pads, i heard they were crap. What little carbon they do put into the filters is quickly used up.

After the carbon absorbs a certain amount of odors, it starts to get full. If the amount of odors drops in the room, if the carbon is saturated enough, it can actually start to release the odors back to balance out.

 

[POTential]

I wish I had a way of measuring cfm but the airflow from the 85cfm fan was cut considerably. Ventilation through a scrubber is not effective for heat control and forced me modify my own cool tube to keep the temps down. Since you already have that advantage I wouldn't hesitate with your experiment. Let us know how it works with the whole center filled with carbon.

the pads are crap

 

[Keith Lake]

These little pocket sized meters are used to measure laminar air flow

Balkowitsch Enterprises - Products

I've seen them cheaper then $200, maybe try ebay - I'd think a used one would be $40 or $50. .

I've got a lot of experience with plate and frame carbon filters and laminar flow - though my experience is not in the application we are talking about on this forum.

Anyway, I've learned you want to have enough carbon that it doesn't saturate too soon, but not so much that you have an excessive restriction in your air flow.

Generally, the cheapest thing to do is to upsize the fan and go with a little extra carbon so you just use a little extra electricity (plus the one time cost of the fan).

Rule of thumb 1(in my old application anyway) was Flow out/Flow in > 75%
Rule of thumb 2 - pay the little extra for the smaller granules to get more surface area in less space

Qualification -> I was capturing solvent vapor which tends to use up carbon pretty quickly. I would imagine that plant aroma is a much lower challenge load

 

[I<3weed]

I have and extra 50 cfm fan laying around. I figured i could attatch a large garbage bag (around 50 gal), and convert it over to cubic feet. Then i could just time how long it takes to fill up the bag with just the fan and use that as my base line. Then add the scrubber, time it, and figure up how many cfm's i lost.

About the granular carbon: I was just gonna use the fish type carbon, i think it comes in flakes. What applications is the granular used in? If its use for aquariums also, i can just grab that instead. The only place around here thats gonna carry activated carbon is probably the pet stores.

Thanks for all the replys guys, i appreciate the help. Tommorrow i'm heading to the pet store to see what they got as far as carbon goes, then to Lowes for the PVC. Once i get everything together, hopefully my garbage bag trick will give me an idea how much cfm's im gonnna lose.

 

[Keith Lake]

That garbage bag idea sounds like a good idea to me - certainly cheaper than a meter.

The granular carbon I was using was made for plate and frame carbon filters - when the carbon became saturated we just changed it out. These filters had 12 per bank and each held about 40 pounds of carbon - so I was a pretty large scale.

I think you are probably heading in the right direction to stay with easily available supplies.

Good luck and tell us how it worked out.

 

[POTential]

I have and extra 50 cfm fan laying around. I figured i could attatch a large garbage bag (around 50 gal), and convert it over to cubic feet. Then i could just time how long it takes to fill up the bag with just the fan and use that as my base line. Then add the scrubber, time it, and figure up how many cfm's i lost.

About the granular carbon: I was just gonna use the fish type carbon, i think it comes in flakes. What applications is the granular used in? If its use for aquariums also, i can just grab that instead. The only place around here thats gonna carry activated carbon is probably the pet stores.

That garbage bag idea is brilliant! I will definitely be testing that out in the future. As for the the carbon, the stuff sold at pet stores will easily be the grade of, or better, that the granular. Just make sure you don't get the pellets as they are bigger than the granules.

 

[I<3weed]

Yeah, i thought of the bag idea today when i was high in the shower.

 

[POTential]

^ haha good shit

 

[I<3weed]

Ok, heres the update. After 2 pet stores didnt have crap for carbon, I finally found some at a local pet store. Then a quick trip to Lowes and i got everything i needed.

I did the garbage bag trick with a 45 gallon trash bag. This is an estimate cause i forgot to check the box to see what size it was, but i think thats about right, i'll check the box when i get a chance.
The carbon i found, $25

First i went huge, i did a 12" x 4" tube of PVC filled with carbon.No air could flow through.

Next, i did a little less(i forget, around 5-10 inches) and still i got no air flow.I went down to 2.25" and finally got some air to flow through, my results....

45 gallons = 6 cubic feetSo my 50 cfm fan pushed 6 cu ft of air in about 6 seconds = 50 cfm
With the scrubber attatched it pushed 6 cu ft of air in 60 seconds =5 cfm
So with 2 1/4" of carbon i lost about 90% CFM.

Now i was doing all this at like 3am last night, so my math may be off a tad and im gonna run a few more tests. Now heres where i screwed up. First i was testing with the fan off,all hooked up to the bag, and switched the fan on. What i ended up doing instead, was turn on the fan and slide the bag onto it while it was running. This eliminated the start up time of my fan and made my time #'s much more consistant.

Also, I didnt rinse the carbon before i started using it (i was super excited to get started), so i've rinsed it out now and am drying it out. I think its gonna help out alot the with air flow with all that dust gone.

I've started to realize now what scrubbers are, they're air filters, just like on your car.* So i started thinking what they're shaped like; ya got the flat square, the cone, and the round tube ones. So my dumbass tried to make an air filter 12" deep and 4" around and thought i was gonna get airflow through it. So if u go back to that first doodle i drew of the canister filter, those scrubbers have around 1-2 inches of carbon surrounding them, but instead of trying to pull air through a 4" hole, its pulling it through 2 sq ft round surface.
The scrubber with the 50 cfm fan on it:

 

[referman]

Hey, I've got a budding room thats about 800 cu. ft. Was thinking of using a 450 cfm squirrel cage blower with a 16X20X1 carbon impregnated filter on it. Do you think this will be enough or should I try the scrubber routine. I don't grow in a high density neighborhood. Any suggestions?

 

[I<3weed]

(everybody hands up this is a highjacking)

Playing with ya.* I only know from what i've read and with no actual experiance what so ever. With that, the carbon impregnated filters are not sufficent for a grow (ok maybe with just one plant), the filter holds very small levels of actived carbon and will do little to no good(according to some HVAC specialists its just a gimmic) on odor control. U definatly need to go with a scrubber or ozone (ozone = more expensive, but better). I suggest the DIY canister type scrubber metioned earlier in this post, im most likely gonna go w/ this design after my own design turned out kinda backwards.

 

[referman]

Thanks for your response. I've never used those filters either and was hoping for a cheap way to clean the air. I will start brainfarting on it now as I have a couple of weeks to get it together. If I come up with a good idea I will post it for everyone.