DIY Carbon Filter Step-by-Step Guide [+Why you Need One]

Creating an optimal environment for your plants is important for a healthy, robust harvest. One way to help create the plant’s natural environment is by using a grow tent in your hydroponic setup.  Using a grow tent for your hydroponic endeavor helps create the plant’s natural environment by using fans, lights, as well as providing an adequate supply of water and nutrition. Grow tents are popular because they allow creative use of growing spaces- allowing you to turn an unused garage or closet into a grow room! 

Grow tents have risen in popularity due to their energy efficiency, giving you a maximum return on your investment. And as with hydroponics, grow tents offer year-round pest-free gardening.

When it comes to your grow tent, making sure to have proper ventilation is key for your plant’s health. This can be easily achieved using a carbon filter!

What Exactly is a Carbon Filter?

A Carbon filter, also known as a scrubber, is a piece of equipment attached to the exhaust system of a grow tent. It is made of activated carbon material, which has been widely for centuries for its detoxification properties. Carbon filters are usually attached to the inline duct fan or the tail end of the ducting. This allows the carbon filter to clean the air circulating throughout.

How Do Carbon Filters Work?

Using a carbon filter as part of your exhaust system literally traps the smell, dust, spores, pollen, and other contaminants. When the unclean air is drawn in through the exhaust system, it is processed and comes out of the room purified and free from any odors. 

As you may expect, the result is cleaner air for your plants. This air is fresher, free from odors, spores, and other allergens. And yes, if you have an odor problem from your plants, a good carbon filter can help!

Benefits of Using a Carbon Filter for your Grow Tent

The benefits of a carbon filter are quite numerous and, as we mentioned earlier, include controlling odors, ventilation assistance, elimination of airborne pathogens and impurities, and healthier plants. And if your legal plants emit any unwanted odors, a carbon filter will do the trick. Just be sure to use finely ground-activated charcoal, which ensures powerful filtration.

You can either buy one of the many carbon filters on the internet, which will cost you around $100, or you can Do-It-Yourself if you’re on a budget and are feeling handy! It is actually pretty simple to make and will save you quite a bit of money. We will run you through how to DIY so you can save yourself some money and help your plant babies in return.

But first, let’s discuss the parts of a carbon filter.

There is a pre-filter that serves as the first line of defense to trap dust and large air particles and contaminants. It is usually made of a semi-transparent and breathable material.

Next up is the activated carbon bed, which is the one-legged unicorn of the carbon filter. Treated charcoal is used to remove odors and pathogens, leaving only clean air to continue passing through to your plants.

The last component is the air passage. The air passage is the cylindrical space in the middle of the filter’s two flanges, which must have the exact diameter as your ducting or inline fan. You want the tightest fitting possible, but don’t worry, we will walk you through everything you need to ensure an awesome DIY carbon filter.

Based on a 4-inch ducting system, we will lay out the supplies you need to get started. You likely have many of these lying around your house already, just waiting for you to use them for this project. If your ducting system is larger than 4 inches, you can improvise on the supplies and measurements as needed. Below is a rough list to help you get started on your first DIY carbon filter!

diy carbon filter for grow tent

Supplies Needed for DIY Carbon Filter:

  • For the Pre-filter- A polyester filter media such as knee-high socks will do
  • For the Body (outer mesh)- A mesh pencil holder (~4.5 inches) Mesh bin
  • For the Body (inner mesh)- A mesh pencil holder (~4 inches), PVC Drain Pipe 
  • For the Activated Carbon Bed- activated carbon
  • Scissors
  • Zip ties
  • Measuring tape
  • Drill Machine
  • Drill bit (5/32 if possible)

Next, we are going to walk you through how to build an easy and effective carbon filter using household materials.

Firstly, make sure the size of the outer and inner mesh complement one another. They will serve as the frame for your entire filter, so this step is necessary to make sure the meshes line up, one over the other. A few things to consider during this step are the height, diameter, and distance of the mesh holders.

Make sure the height of the smaller holder is around ½-¾ of the height of the bigger holder. For the distance, 12-24mm is the space between the bigger holder and the smaller holder inside. As for the diameter, ensure the smaller holder is equal to the diameter of the ducting for the tightest possible fit.

Depending upon how porous your pencil holders are, consider drilling holes in them to ensure air can pass through on all sides of the holder. Using a very small drill bit as we mentioned earlier works best.

Next, you’ll want to grab your socks and insert one pencil holder per sock. If you stretch out the sock opening first, it makes it easier to insert the cup bottom part first. Then you can pull the sock up for full coverage on both pencil holders.

Finally, time to get in on the carbon action! Carefully pour the activated carbon inside the large pencil holder, only filling about halfway. 

Next, it’s time to secure the activated carbon to prevent any carbon from being wasted. Place the inner mesh on top of the carbon inside the larger cup, and pull up the sock of the larger cup all the way over the smaller cup, too. Carefully turn it upside down once the carbon is sealed in safety, which will properly distribute the carbon. Once complete, turn the setup into an upright position. It is very important that the rim of the inner mesh is oriented with the level of the rim of the outer mesh.

Secure the positioning of the smaller cup’s sock by stretching it out and bringing it all the way over the exterior of the larger cup. Keep adjusting as needed until everything is equal on all sides. Once this is complete, you’re ready to attach your DIY carbon filter onto your ducting or inline fan.

Place your filter tightly into the ducting, making sure it cannot be moved or twisted. Once you’ve got it locked in place, grab those zip ties and fasten it up. And now you have your very own, DIY carbon filter!

If you’re still on the fence about carbon filters and you use a grow tent, get off the fence and get started on your first DIY carbon filter project. The benefits for your plants are numerous, including better quality and taste, and if you prefer an odorless grow tent a carbon filter is the only way to go.

Before we go, check out this video of a DIY carbon filter so you can see for yourself just how easy it is to make at home:


Does the Carbon Filter Go Inside or Outside My Grow Tent?

The carbon filter can go either inside or outside your grow tent, depending upon your needs, space, and setup. To set the carbon filter up inside your grow tent, attach it to one side of the tent, and the fan to the other side near the exhaust port. You can run ducting from the filter to the fan, then from the fan to the outside of your tent. Once this is complete, test to make sure the fan is pulling air from inside the tent to outside the tent. The inside setup will give your grow area a clean, sleek look. 

If you’re low on space inside your grow tent, you may prefer to set up your carbon filter and fan outside of your grow tent. To do so, fasten the ducting to the top of your grow tent, near the exhaust port. Now you can run the ducting from inside the grow tent- through the exhaust port- to the outside of the tent. Next, attach the carbon filter to the fan. You should always test to make sure the fan is pulling air from the inside of the tent to the outside.

How Often Should You Change your DIY Carbon Filter?

Once a year, think about replacing your carbon filter. Over time, carbon filters lose their effectivity, especially if your grow tent demands heavy use. Around 12-18 months is a solid timeline to stick to when changing out your DIY carbon filter. Keeping the carbon filter fresh ensures your plants get only the freshest, cleanest air!

High Tech Gardening