Carbon filters are something you’ll see in almost every grow room with some kind of fan system flowing air around. They are currently the top product that is used in odor reduction when growing cannabis.
As you know, cannabis can be quite pungent throughout its lifetime.
Starting at the end of the vegetative state and getting progressively stronger throughout the flowering cycle, until harvest when it’s the smelliest. Cannabis has a distinct and strong smell that can permeate throughout your garden, house, or yard.
This is why carbon filters are important parts of your cannabis ventilation system as they will absorb the majority of the smells from your plant.
It is important to note that carbon filters won’t eliminate 100% of the smell (nothing will) but they will reduce it enough that you have a chance at not being inundated with a fresh cannabis smell.
Before you can tackle why you can still smell cannabis even with a carbon filter, let’s look at how they work in a cannabis grow room.
What is a carbon filter?
A carbon filter is something that eliminates odor in the air and that’s why it is used extensively in the cannabis industry. It is made out of spongy materials that are used to trap organic elements, this is thanks to the activated carbon inside.
Carbon in the form of charcoal is incredibly absorbent because of how porous the surface is. When you activate it through special vapor treatments and high heat it becomes so porous that it can absorb almost any natural element on the planet.
In fact, it is extensively used in water filtration (reverse osmosis), air filtration, and cosmetics.
Using a carbon filter in a grow room can reduce the number of airborne bacteria in your grow space from 10,000 parts per million to under 100. Cannabis grows best with fresh air and if there are fewer particles and bacteria in the air then your plant will be able to absorb more C02.
Carbon filters for cannabis generally come in a tube or cylindrical shape.
Inside the house are layers of charcoal pellets that form a wall that air has to pass through. That’s where the magic happens. Any air that passes through the filter has to go through the activated charcoal. The ions in the activated charcoal attract the scent molecules and hold onto them, which is why you don’t smell it as much as it’s coming out of the filter.
Make sure to smell-proof your grow area
A carbon filter can only do much to prevent the cannabis smell from leaking out. A lot of times growers can mistake a leak in their grow tent for a failing carbon filter. This primarily happens in tents with small rips or holes in the fabric.
Another culprit of the cannabis smell is a leaky zipper, usually found in some of the cheaper tents. Leaky zipper refers to the tiny holes between the zipper teeth that allow cannabis smells to leak through.
More expensive tents come with a flap that covers the zipper to mitigate any odors from escaping.
You generally won’t see this issue with professional grow rooms that are properly built because they are sealed to protect the plants from airborne molds such as powdery mildew. Only if there is a failure in the air system will you see smells escaping outside.
Troubleshooting your carbon filter
If something is going on with your carbon filter you’ll know by the smell.
It should be inspected to make sure that everything was installed correctly, this includes all the connections used to put the system together.
Activated carbon in the filter can be affected by climate changes and this is usually the second thing to look into once you make sure everything is installed and connected.
If you’re using a grow tent then having the carbon filter outside of the grow tent is a good idea so it doesn’t get affected by high humidity from inside the tent.
Carbon filters have expiration dates so make sure you mark that down in a book when you purchase it is a good idea. Using a carbon filter past this expiration date runs the risk of it no longer being effective.
If your humidity is in the higher range, such as 80% when you are trying to raise clones or seedlings, it can cause the activated carbon to compact and lose the ability to grab those scent molecules.
It’s the pores within the charcoal that captures and holds the scent, once those pores are gone the filter will do nothing. This is why most grow rooms have their charcoal filters on the outside of their grow rooms with fans sucking the air out to the filter.
Perform regular maintenance
As with everything in a cannabis garden, a carbon filter also needs some care and attention. Knowing that carbon filters are compact by high amounts of humidity means that any moist air that goes through the filter is a bad thing.
Don’t have your exhaust fan on if you are spraying your cannabis with a foliar spray. The damp air will get sucked out through the carbon filter and accelerate the compaction process. As the carbon filter compacts less air can flow through which makes your exhaust fans work harder, eventually burning out your motor.
Keep your filter and accompanying sock clean from debris and dust.
The idea is to eliminate anything that impedes the flow of air. Speaking of air, make sure you buy a carbon filter that is stronger than the fan feeding air to it.
You want to keep a maximum airflow rate and the extra space allows for a longer time before you will need to clean the filter.
Check your carbon filter at regular intervals
As you can see the main problems you’ll come across when you start smelling cannabis even with a filtering system are improper installation and a failing filter.
If you keep up with a proper maintenance regimen then you will notice something before a problem happens.