Intro: Sew Your Own Carbon Air Filter for $10
Need to deodorize some air? If you can sew, this is a budget friendly DIY solution. It uses activated carbon and breathable organza fabric, and is secured with elastic, so you can take it off if you need to. Pictured is my space bucket for growing plants indoors. The classic DIY tutorial for carbon filters in the Space Bucket community is the filter made from pencil holders, but that doesn't work if your fan is too big, or if you can't find the right stackable mesh pencil holders.
The carbon filter does slow down the air flow. I put a wet finger by my passive intake holes on the side of the bucket, and I can still feel air going in, just a little less than before. The fan than I am using is the Stylepie Fun Fun Fan, a high quality brushless USB fan.
- Half a yard of organza (1/4 yard is probably enough if the fabric store will let you buy that little fabric) -- $1-2
- Activated carbon (available at your local pet fish store) -- $6
- 2ft fold over elastic -- $1-2
This instructable assumes that you already have a fan that the filter is meant to fit on. If you are choosing a fan for a space bucket grow, check out the relevant Space Bucket Wiki page. Also I had purchased some collar interfacing fabric that I was going to also test this design with, but after seeing how rough I was with the organza I'm pretty sure the interfacing would just rip. Fine netting would work too but it's more stretchy than organza so it's harder to sew. Cheesecloth fabric holes are too big.
- sewing machine *with zipper foot*, thread, pins
- scissors for cutting the organza
- something that can mark your fabric (tailors chalk, or even just a pencil)
If your sewing machine doesn't have a zipper foot you can buy a compatible one online. I actually did this without a zipper foot (I couldn't find mine at the time) and my seams look ugly, but it's not the end of the world. The zipper foot makes it much easier to sew right beside the carbon.
Note that this is a messy project. You will be getting black carbon dust all over your sewing machine and work surface. I even had to wash my hands a couple times before it came off completely.
Space Bucket Community: https://www.spacebuckets.com/
Airflow page on the Space Bucket Wiki: https://www.spacebuckets.com/wiki/Airflow_Solution...
More info about my grow buckets: https://growbucket.life/
My grow bucket project diary: https://medium.com/grow-bucket-life-project-kickst...
Step 1: Cut Fabric for the Top of the Filter
You will need two piece of fabric for the top so that the carbon can go in between. To make a piece, trace the top of your fan onto the fabric. Cut around the trace with an extra half inch border for your seam allowance.
Step 2: Cut Fabric for the Side of the Filter
You will need two strips of fabric for the side so that the carbon to go in between. You can use your fan to figure out how thick you need your side strips to be. The thickness of the strip should be the height of the fan plus 1 inch, so that you have a half inch seam allowance on each side. The length of the strip should be at least 1.5 times the circumference of the fan, since sewing in the carbon is going to use up fabric. I tried 1.25 times and 2 times the circumference and got it too short and too long. If this happens to you, you can sew and attach an extra carbon pouch if it's too short, or trim the end off if it's too long.
Step 3: Add Carbon to the Top
First, pin the two circles of organza fabric for the top of your filter together. Sew around, leaving an inch gap so you can fill it with carbon (don't forget to backstitch). Put activated carbon in it. I filled mine until the height was about 1/2 inch when lying flat. Finally, sew up the gap.
Step 4: Add Carbon to the Sides
Pin your side strips together. Sew two long sides together and one short side. The remaining open short side is how we'll put the carbon in. Put some carbon in (about a handful). Sew a seam right beside the carbon you just put in. This is where the zipper foot comes in handy -- you can sew right beside the carbon. Put more carbon in. Sew a seam right beside the new carbon you put in. Repeat until your carbon goes all the way around your fan (you can test it to see how much more you have to add). Sewing seams in between the carbon ensures that the carbon won't all migrate to one side leaving a half useless filter.
When you get to the last one, you may need a pin to keep the carbon from falling out while you sew. Be careful not to let the sewing needle hit the pin and wear eye protection while doing this. I broke a sewing needle by sewing over a pin once, and the tip of the needle flew up and hit my eyebrow. It could have hit my eye but I was wearing glasses.
Step 5: Sew the Side Into a Ring
You can see very clearly here that I did this without a zipper foot and it looks very messy. Use a zipper foot if you have one. Sew the ends of the side strips together, making sure that it fits over your fan. Trim excess fabric off. Tack (sew back and forth over) your previous stitches to prevent them from unravelling if you are cutting the seam when you trip the excess fabric.
Step 6: Sew the Top Onto the Sides
Put the sides of the filter onto the fan with the raw edge of the place where you sewed the ring facing OUT. Put the top of the filter on top. Place two pins attaching the side to the top across from each other. Place another two pins in between the first two pins. The pin placement ensures that your side will be evenly attached to the top. Sew the top to the sides.
Step 7: Attach the Elastic
Flip your carbon filter so that the raw edges are all on the inside. Cut your elastic so that it is a couple inches shorter than the circumference of your fan when it is not stretched.
On the bottom edge of your carbon filter, mark where you are going to start sewing the elastic, and the halfway point across from that. On your elastic, mark the halfway point down the length.
Sew the elastic onto the bottom edge of the filter so that the wrong side of the elastic is touching the outside side of the filter, stretching the elastic as you sew. Make sure that the middle of the elastic matches the halfway point on the bottom of the filter. Afterwards tack the ends of the elastic to each other.
Congratulations! You've made your carbon filter! Now you can take it on and off your fan.