How to Make a Carbon Filter for A Grow Room?

A DIY carbon filter for your grow room?

Why not?

Therefore, a DIYer grower would at least give it a shot. Who knows, it can literally end up saving some hard-earned bucks of yours.

You see, a good quality carbon filter costs near around 100 bucks. But it’s nothing but some activated charcoal trapped between two meshed metal sheets. But the harsh truth is- The materialistic cost would be at least 1/3rd of what it costs in the market.

If you feel like making your own grow room carbon filter, let’s dive right into the guide-  

What Are The Essential Parts of A Air Carbon Filter?

Before we dive into the steps, I’ll take two more minutes to discuss this.

Basically, carbon filters can be for both water and air purifying. And we’re clearly up to the second type.

Air carbon filters have four parts-

The Pre-filter

Pre-filter is the breathable, semi-transparent medium around the carbon filter body. It has minimal air resistance so that it can let the air pass through the carbon bed. Its main purpose is to defend the dust particles and debris from entering into the carbon.   

The Body

Outer mesh, activated charcoal and inner mesh- these are the components of the ‘body’. Securing a dust-free air intake through the pre-filter, it lets the air pass through the carbon layer. Finally, smell and odor-free air enters into the air passage and gets towards the flanges.

The Activated Carbon

This is the most happening part of the whole process. Activated charcoals, with the uncountable pores, draws the smelly chemicals in, and supplies smell and dust free air on the other side.

Usually, 1050+ Australian Virgin Charcoal is treated as the most effective activated carbon for growing diy carbon filter air purifier.

The Air Passage

The air passage is the cylindrical area between the two openings(flanges) of the filter. It can be anything from 4″ to 8″, based on your ducting system.

The flanges are must-to-be of the exact diameter as the ducting and inline fan. Otherwise, the whole purpose of the filter will be ruined.

Note: Learn more on carbon filters, their types and functions here.

DIY Carbon Filter for Grow Room: What Items Do You Need?

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We want you to pay some serious attention here.

Here is a chart of all kind of products(and alternatives) that you need throughout the process to build carbon filter grow room

The Pre-filterOver The Knee High SocksTOCONFFON Women’s Over The Knee High Socks
Polyester Filter MediaAirstarFilters Air Filter Media Roll
The BodyMesh Trash Bin(Outer Mesh)Oranmay 9.84” Metal Mesh Wastebasket
PVC Drain Pipe(Inner Mesh)Ads Sewer And Drain Pipe 4″ X 10′
4.75″ Mesh Pencil Holder(Outer Mesh)Staples Silver Wire Mesh Jumbo Pencil Cup
4” Mesh Pencil Holder(Inner Mesg)WJX&LIKERR Metal mesh Pen Pencil Holder
Bamboo Activated Charcoal(Small)Drive Natural 220g Moso Bamboo Activated Charcoal
Bamboo Activated Charcoal(Medium)Health+ 8-pack Activated Bamboo Charcoal

Other Tools Required

  • A pair of scissors.
  • Measuring Tape.
  • Zip ties.
  • Drill machine.
  • 5/32 drill bit.  

Steps to Make Your Own Carbon Filter

Alright, we’re at the heart of the post now-

There are some steps for preparing a carbon filter for a 4″ ducting setup in mind. If you have a 6″ or 8″ ducting, you can take similar items of higher diameter/dimensions.

We’ll explain more on it later. For now, let’s get going with the steps-

Step 1: Prepare the Two Pencil Holders

The two pencil holders are the backbones of what we’re about to create. So, their sizes should complement each other.

We’re talking about the heights, the diameters and the distances of them when you put the smaller one into the bigger one.

Here are the rules-

  1. The height of the smaller cup should be about 3/4th of the height of the bigger cup.
  2. The diameter of the smaller cup should be exactly the same to the diameter of your ducting.
  3. The distance between two cups(while smaller ones into the bigger one) should be 12-24mm.

Step 2: Drill Holes on the Bottom Surface of the Cups

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To make sure that the cups are permeable from all sides, you should drill 8-12 small holes on the bottom of each cups.

As these cups are made of delicate metals like aluminum, you should be careful with the drilling. If you use a drill machine, you should go for bits as small as 5/32.

A set of uniformly drilled holes on the bottom will make them air-transparent.

Step 3: Put Both of the Cups into the Socks

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We’re going to put both of the cups into the socks now. Take one sock for each of the cups and stretch the sock openings. Now put the bottom side of the cups into the sock, and wrap the sock around it.

Continue the same process with the other cup as well. Make sure they are uniformly covered up all over the round surface.

Step 4: Fill them Up with Activated Carbon

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Get the activated carbon to fill up the bottom of the larger cup until it fills up half of the length of it at the bottom side.

Make sure your activated charcoal is finely granulated, and uniform in size. Larger sizes of activated carbon particles ruin the whole process, specially in case of small carbon filters like this.  

Step 5: Seal the Activated Carbon Within The Two Cups

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As you put the small cup onto the carbon filter surface, the two cups won’t be at the same height. You need to pull the sock up to the insider cup and cover its body with the sock.

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Now, hold the setup upside down and let the activated carbon be evenly distributed within the gap between the two cups.

Meanwhile, make sure that you’re holding up the sock securely, and making an even space around the two cups for the activated carbon.

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Also, make sure that the space between two bottom surfaces of the cups is not left empty. An equal thickness of activated carbon should also be present there.  

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As it’s done, bring the two cups to the upright position once again. Make sure to adjust necessarily, so that the openings of the two cups stay on the same level.

Step 6: Adjust the Socks

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Now, you need to pull off the sock of the insider cup. Pull it off and place it around the outer cup. Make sure that the pulling is completely even.

If done properly, this will ensure a clear edge of the middle-cup and also provide with a secure end.

Step 7: Attach it to Your 4” Ducting/Fan

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We’re almost finished with putting our newly made carbon filer into work.

Take the filter out and re-check for the secure positions of both of the cups. Now, fit it into the 4″ ducting or inline fan of your grow ventilation system.

Secure the connection with a bracket/zip tie, and keep it twisting until there is a snug lock takes place.

To double-check whether the connection is strong or not, try to circulate the carbon filter around the duct/fan. If you can’t then you’re good to go.  

Things to Keep In Mind

  1. If you’re up for to make activated carbon filter, you should never choose pencils cups with unequal diameters at the top and bottom openings.
  2. While distributing the carbon within the gap of two cups, make it 100% certain that the distribution is even around the whole perimeter.
  3. Make sure that the central axes of the two cups are on the same line, and the two openings are on the same level.
  4. To secure the two pencil cups together, you might consider using some duct tape.
  5. Change your carbon filter on a regular basis, as long as you find the odor filter not working anymore.

What if You Need A Bigger Carbon Filter?

This is an obvious question that we expect from growers who are with bigger growing size. They definitely need a way stronger DIY carbon filter comparing the 4″ version.

For the items you need to make your own activated carbon filter of larger size, if you go back and have a look at the ‘What Items do You Need?’ part again, you’ll find your answer.

As can see, a number of alternatives(of the items we’ve used here) had been kept in the table. Some examples are-

  1. Mesh trash bin instead of large pen cup.
  2. PVC drain pipe instead of a smaller pen cup.
  3. Polyester filter media instead of socks.  
  4. Duct tapes instead of no duck tapes at all.

All these alternatives you can see above, are the choices for constructing a larger and bigger carbon filter. Hence, you’re on the way to complete diy grow room odor control. Hopefully, this guide on how to make a carbon filter for a grow room gave you a good hand in this regard.

1 Comment
  1. what kin of FAN do you recommend? PC strong enough? 34cfm, 2000rpm?

    Leave a Reply to Mike Cancel reply