carbon filter not stopping smell

Carbon Filter Not Stopping Smell: 4 Instant Solutions

You don’t want your entire house funk to high heaven, right?

You see, apart from the cultivation process another major struggle of us growers is controlling the smell. In this case, you can use a carbon filter to stop the smell from going out.

But what to do if your carbon filter not stopping smell?

Carbon filter doesn’t stop smelling when it gets fully packed. Also, your wrong size filter can be the reason. However, replacing your filter with a new one can be a good solution. But make sure you install your filter correctly. Moreover, you can use an alternative as well. 

Relax! This isn’t James Bond’s final mission. I’m gonna surprise you with more intriguing information you might’ve not considered before. 

So, stay tuned with us-

Does a Carbon Filter Remove 100% Smell?

Basically, the odor in the grow room is produced by the terpenes embodied within the marijuana. Therefore, using a carbon filter you can release odorless air from your grow room.

However, does a carbon filter remove your grow room smell entirely?   

Generally, a regular carbon filter comprises approximately 5 pounds of carbon. It can actually load up somewhat instantly. Especially in an indoor condition like a weed grow room. 

Because the level of air contamination in such places is pretty high. So, you can say that the filter will continue absorbing all the smell until it’s entirely loaded. 

I’ve installed an air quality sensor in my grow room. It helps me to keep the air quality in check. Therefore, I can easily understand if my carbon filter is doing its job or not.

So, from my good experience, I can suggest the following sensors. 

However, you can safely use one carbon filter if you’re planning to yield 1 pound indoors.

But after it’s packed, it’ll start re-releasing all the gathered smell back in the room. If any such thing occurs you might say….yikes! These filters are useless!

You see, it all comes down to maintenance at the end.

Nevertheless, some more factors can interrupt the good business of your carbon filter. Let’s uncover them in the next section.  

Why is My Carbon Filter Smelling?

In the previous section, we saw carbon filters actually have 100% capability. Still, they might not completely stop your grow room from smelling. 

Here’s why-

Reason 1: Wrong Filter Size and Material


Well, your filter’s size and the size of your exhaust pipe should match. Otherwise, the airflow of the room will be disrupted. Hence, the carbon filter won’t be able to eliminate enough smell.

In this case, I’ve always used the following CFM meter gauges interchangeably. It helped me to choose the accurate carbon filter CFM.

These best budget meters will definitely help you in CFM calculation.

Reason 2: Dirty Prefilter On the Carbon Filter

The pre-filter prevents dust from clogging your carbon filter. Otherwise, the durability of your carbon filter will be compromised. 

However, if the prefilter hasn’t been cleaned or replaced in 3-6 months, it’ll stop protecting your filter.

In that case, your filter will be full of dust and totally ineffective.

Reason 3: Faulty Setup

The setup of your carbon filter and your air-cooled reflector setting should correctly align. 

You need to check if the filter is properly sealed to your Vivosun exhaust fan. Otherwise, the fan will grab air around the filter and pass reeking air everywhere.

You might yet smell foul air if the ducting is leaking in front of the filter.

Reason 4: Grow Tent Leaking [Carbon filter ain’t the culprit]

Sometimes your grow tent might start leaking the smell. This happens when the negative pressure of your tent is less than the positive pressure.


Because negative pressure helps the tent to suck in some fresh air. Otherwise, the tent will start leaking out the smell.

How to Fix the Smell Issue?

So far, we discussed all the possible reasons for the carbon filter not stopping the smell. Now, it’s time for the remedies!

Excited to kick the problems out of the door? Me too! So, let’s jump into the next section-

Fix 1: Set Up Your Filter Correctly

To set your filter correctly you need to follow two steps. Once you’re done setting it up accurately, the filter will work effectively until it’s expired. 

So let’s learn the process-

Step 1: Find the Right Size

Generally, carbon filter size varies according to your grow room and the CFM value of the fan. Now, let’s see how you can calculate the CFM value.

But before that, you’d need the following tools. These equips will definitely help you to do your calculation quickly. Take a look-

The best option would be to match the CFM of your filter with the CFM of your exhaust fan. 

For your convenience, let’s look at the following example-

Suppose, you got a 5ft x 5ft x 8ft grow tent, therefore the calculation would be:

Now that you know your convenient size, let’s find out how you should set up your filter.

Step 2: Set Up Your Filter

This step is the most important one. Because the more accurate the setup is, the more effective the filtration would be. Hence, you need to carefully follow the instructions here. 

Let’s start now-

  • Start with connecting the filter with the exhaust fan and ducting. Then seal it completely. You can use any of the following duct clamps for the sealing.
  • Next, you need to position the filter and fan high up or close to the plants. Then, place the fan in a position where it’ll draw air from the grow tent. And then it’ll drain the air into the filter. 

In this way, no air will leave the room before passing through the filter. 

So, now you know how to place the carbon filter for proper smell control.

Fix 2: Cleaning the Dirty Media

You should clean your carbon filter, including the pre-filter once a month. How and why? Watch the following video to know more-

However, pre-filters aren’t that expensive. So, if you don’t wanna take the hassle of washing, just replace it.

Some reasonable and best quality pre-filter recommendations are given below-

Now, if you want to clean your carbon filter we would suggest dry cleaning. Otherwise, the charcoal may break down and decay quickly if you use water.

Let’s look at the following picture to know how to dry clean your filter. But before that get yourself a handheld vacuum and a cleaning brush.

However, if you still notice the smell after cleaning the filter it’s time to replace it. Fear not! I’ve changed so many filters till now. So, here I’m recommending the carbon filters which were durable and absolutely reasonable.  

Your job doesn’t end with replacing the filter. Now, you need to help it to perform better. How? 

Let’s find out in the next section- 

Fix 3: Help the Carbon Filter

If you want your filter to work properly then you should keep the humidity under 70%. Because with increased humidity the smell gets stronger. 

In this case, you can use a dehumidifier. My best choice has always been the Inkbird dehumidifier. It’s easy to use and comes with alarms and sensors for emergencies.

Also, you should pull 20% less air than you extract by sealing most of the vent holes. In this way, the negative pressure will be maintained in your grow room. 

This is actually great for maintaining the odor. Because negative pressure helps to replace the smell with fresh air.

Fix 4: Commercial Alternatives to Stop the Smell

Still no luck with the carbon filter? Then you better look for an alternative. You can use it separately or along with the filter for a better outcome. 

So, let’s find out what substitutes are available in the market. 

These are some of the alternatives that can be useful along with your carbon filter. 

Carbon Filter Still Smells?

If you think you’re unable to identify the problem of your filter, consult someone experienced. Let them check your filter. Most likely they’ll be able to suggest solutions.

Otherwise, you can also consult a trusted agricultural officer. They are experienced and knowledgeable enough to identify the need of your filter.


From which distance can you smell a cannabis plant with buds?

It totally depends on the number of cannabis strains you have. You see, some buds spread a strong smell. On the other hand, some buds have no kind of scents.

How do I remove the smell of cannabis from my car?

You can purchase a box of Breezeo fabric softener sheets. Then allocate it in the glove compartment, in the trunk. You can also place it on the driver and passenger sides.

How long will carbon filters last in a grow room?

Suppose you maintain a 10 4 x 9 table and there are 55 plants in each table. And you have 400 CFM fan. In this case, the carbon filter should last till 4-5 crops.

Parting Roll

Hope you don’t have to worry about your carbon filter not stopping smell anymore.

However,  don’t wait until your carbon filter starts showing dysfunctional symptoms. Instead, replace your filter with a new one according to a usual schedule. 

Enjoy your gardening!

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