Do-it-yourself charcoal filter for growbox

The heading “crazy hands” is gaining momentum and today we have prepared instructions on how to make a charcoal filter for a growbox with your own hands. But first, some useful information to broaden your horizons. Look for a humidifier for grow tent.

Odor control properties of coal

The basis of any carbon filter, which in principle is clear from the name, is activated carbon. Activated carbon is 97% carbon and contains virtually no impurities. The structure of charcoal is composed of crystals of amorphous carbon and graphite, which makes it highly porous and ideal for filtering polluted air. Due to the chemisorption process, the pollutant molecules are absorbed on the surface of the activated carbon and this process is irreversible.

We wrote in this article for more information about why a filter is needed when growing indoors and how to choose a ready-made filter. If you still plan on building your growth box filter yourself, use our step-by-step guide below.

Required parts and tools

What you need to assemble the carbon filter:

  • air filter from a car (we use a filter for a GAZ car);
  • Activated carbon;
  • galvanized flange with a diameter of 100 mm;
  • washers, nuts, rivets;
  • drill with a drill 4 mm;
  • jigsaw, soldering iron, metal scissors.

The choice of an air filter for a car is due to the fact that it already has the mesh we need, which greatly simplifies the task of creating a carbon filter.

Assembly stages

The first step is to get rid of the filter paper.

It is held in foam and comes off easily with normal heating. However, do not use a lighter to heat it up – it will take too long. A hotplate is perfect for this manipulation. Place the filter lid on the hotplate and wait a while until everything is heated, carefully remove the filter (do not forget to wear gloves!) And take out the paper.

The second step is to reduce the diameter of the inner mesh.

Since our flange is 100 mm, the inner mesh must be reduced with metal scissors.

The third step is to rivet the outer mesh.

In the place where you placed the flange, you need to connect the cover with the flange itself and the outer mesh. You should get something like this.

The fourth stage is to solder the nuts.

On the back of the filter, we solder the nuts into which the screws will be screwed. This is necessary in order for you to be able to replace the spent coal.

The fifth stage is final.

Finally, we spray the entire structure with activated carbon. It is advisable to do this on a shaker for good tamping and close the lid. Do not forget to seal the foam rubber along the ends of the filter, it is necessary to compensate for the vacant space after coal is tamped.


You get a carbon filter 22 cm long, 18 cm in diameter, a 100 mm flange protrudes 6 cm, if the flange protrusion gets in the way, a grinder will help you.

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