Lush, large, and crystal-like resin covered buds mean your cannabis plants are in the flowering stage.
While this is good news for your yields, the unique odor that comes alongside may become disturbing to some people.
For indoor growers, this could be exciting and rewarding. The aroma is tolerable, normal even. Yet, odor control is crucial especially if this becomes inconvenient to your neighborhood.
Generally, it’s either you cover up or scrub away the scent out of the air using a carbon filter. There’s no way to totally remove the odor. It’s all about finding the right solution on how to control it.
Hence, we’ve created this post to explain all simple ways Controlling Smells & Odors from Your Indoor Cannabis Grow Room or tent. We’ve also included cheap methods on how to smell proof a grow room.
These include using inline fans, carbon filters, and odor cover-ups. You can use either one of these or combine some to obtain worry-free marijuana grow space.
Now, the smell of marijuana or the smell of money coming from growing marijuana? Why not both?
Discover guided steps so you won’t have to worry much about the scent, and keep the produce and money flowing instead.
- Where Does the Smell Come From?
- What Strengthens Odor in a Marijuana Grow Room?
- Humidity Levels and Temperature
- Proper air circulation is important
- Effective Solutions in Controlling Odor in a Marijuana Grow Room
- 1. Install Carbon Filters or Scrubber in the Exhaust System
- 2. Use Inline Fans
- 3. Consider Odor Cover-Ups or Neutralizers
- Can Air Purifiers Remove Odor in a Marijuana Grow Room?
- Should I Use an Ozone Generator to Mask the Smell in a Weed Grow Space?
- Key Takeaways
Where Does the Smell Come From?
Cannabis plants that are in their vegetative stage sustain a very low scent because they haven’t produced terpenes– the molecules responsible for the aromatic properties of a marijuana plant.
A weed plant will develop trichomes when it transitions to the blooming phase and starts to produce flowering nodes.
The trichomes are the molecule factories that create plenty of aromatic compounds.
What Strengthens Odor in a Marijuana Grow Room?
If left uncontrolled, the stench will remain in the air, eventually permeating an entire grow space.
Humidity Levels and Temperature
High humidity and temperature can prolong cannabis scent in a grow room. Therefore, the first step to consider is whether you’ve set the proper temperature and relative humidity.
Certain strains may have a particular need, but these are the recommended humidity levels in various phases of marijuana growth.
- Cloning Phase = 70% to 80% humidity
- Vegetative Phase = 40% to 60% humidity
- Flowering Phase = 40% to 50% humidity
- Final Weeks of Flowering Phase = less than 40% humidity
Proper air circulation is important
Proper air circulation helps maintain temperature and cannabis odor low in a grow space. Additionally, it can recycle used CO2 out of your grow space.
Thus, ensuring your grow space has the right air circulation keeps the appropriate temperature and relative humidity.
Grow lights emit heat in variable quantities. Hotter systems like ceramic metal halides (CMH) and high intensity discharge (HID) might find it more difficult to suppress heat.
Yet, smaller lighting systems like Light Emitting Diodes (LED) and compact fluorescents have their own struggles as well.
All growing lighting systems can discharge hazardously high temperatures if there isn’t suitable air circulation and ventilation.
Generally, air should be able to circulate around a grow space every few minutes during the vegetative stage and every minute during the blooming stage.
The most convenient way to guarantee air circulation is to install either standing or oscillating fans.
When fans are paired with ducted intake and exhaust fans, it becomes easier for the air to move around, taking the smell out with them.
Effective Solutions in Controlling Odor in a Marijuana Grow Room
For proper grow room odor control It’s highly possible to cover up the scent if you only have 1 to 2 plants in a small grow tent.
But if you have a larger grow space, you definitely have to scrub the aroma out of the air.
Here are the top techniques to eliminate the smell from the grow room or tent that every grower can attest to.
With a little experimentation, I’m sure you’ll discover what’s the appropriate solution for you.
1. Install Carbon Filters or Scrubber in the Exhaust System
Like what I said, it’s impossible to totally eradicate the scent, but an air filter with activated charcoal can kill 90% of the cannabis odor in your grow space.
Carbon filters are capable of ‘scrubbing’ contaminants out of the air by emitting activated and highly ionized carbon to draw particulates from the air.
As a result, volatile organic compounds such as mold spores, dust, and hair that carry odor become confined in a pre-filter.
Sometimes, ionized carbon molecules inside the filter’s main cylinder trap those compounds.
Once the filter cleans the air, you are left with fresh air that doesn’t harbor odor molecules.
Here’s a fun fact
carbon scrubbed environments can get the airborne bacterial counts in your marijuana grow space from a whopping 10,000 parts per million to as low as 30 parts per million.
Furthermore, using a carbon filter to control odor in a marijuana grow room is the most environmentally friendly technique.
Note that carbon filters may come 4 to 12 inches in circumference. To determine what carbon filter size you require, you must first identify the cubic feet per minute of your marijuana grow space.
To measure this, simply multiply the length, width, and height.
For instance, you have a 4×4 grow space:
4 x 4 x 6.5 = 104 CFM
Here’s a table identifying the appropriate carbon filter sizes with the average cubic feet per minute (CFM).
- 4-inch carbon filter = 260 CFM
- 6-inch carbon filter = 530 CFM
- 8-inch carbon filter = 780 CFM
- 10-inch carbon filter = 860 CFM
- 12-inch carbon filter = 1765 CFM
How to Set Up a Carbon Filter for Ideal Odor Control
Looking at the table, we see that you can use a 4-inch carbon filter.
Here’s another sample. If your cannabis grow space has a square footage of 500 square feet, then your fan and filter should be capable of handling 100 CFM to achieve 500 square feet in 5 minutes.
In this way, you mitigate the odor by successfully replacing the air in your grow space.
For a 10 x 10 x 12 ft cannabis grow space, this would mean you have 400 as the base number.
Let’s say your space gets around 97 degrees Fahrenheit, which could add 25% of 400 (100) to the base CFM.
If you’re using a CMH light, it’s best to add 15% (60) to take the light temperature into account. Then here’s come the filter, which should take another 20% (80).
So: 400 + 100 + 60 + 80 = 640 CFM
Therefore, your fan must have the capacity to move at least 640 CFM of air to control the odor.
Tip: Make sure your filter has a higher CFM rating than your fan. This is to prevent your fan from being strained by a filter with a lower CFM rating.
It will also guarantee optimal efficiency by only taking in as much air as it can, thereby scrubbing as much air as it can.
I’ve found that carbon filters are less effective in humid conditions. If your growing conditions permit, keep humidity level below 70%.
Moreover, it goes without saying that expensive units tend to use better quality parts. Yet, an average priced carbon filter should last long enough to help control the aroma in your cannabis grow room.
Another trick I’ve discovered is putting an exhaust fan on top of a carbon filter, and then placing the fixture wherever the marijuana odor is strongest.
Recalling what I’ve said earlier, you can combine techniques found in this post. When you choose to install a carbon filter, you can use an odor eliminating gel or spray as a supplement.
2. Use Inline Fans
Using an inline fan boosts the effectiveness of a carbon filter. The fans remove excess carbon dioxide and regulate the environment.
Similar to scrubbers, the CFM determines the right inline fan to control the smell and odor in your cannabis grow room or tent.
Use this formula to identify the best inline fan with the matching CFM capacity: length x width x height (in feet) of your grow space x 1.25 (125%).
The result is the CFM rating of the fan you’ll require. It should be the amount of air your inline fan is capable of removing each minute.
Notice there’s an extra 25% to allow some room in case your carbon filter or ducting pose some resistance.
Given this equation, a fan rated at 260 CFM will exchange 260 cubic feet of air every minute.
The higher the CFM rating, the more powerful the fan is. Thus, this provides more power to control the odor in your marijuana grow room.
Note that inline fans come in different sizes and a range of prices. Also, the noisier models are typically the cheaper ones.
Fan diameters are usually 4, 6, and 8 inches. A 6-inch diameter fan is the most used.
Furthermore, you’ll have to connect outside ducting to the inline fan so hot and stagnant air can flow away, bringing the scent with it.
Don’t forget to place the fan properly so it can function as a vacuum inside your weed grow space. In this way, you’ll know if the air is only leaving through the filter.
3. Consider Odor Cover-Ups or Neutralizers
In the final six weeks of a marijuana plant’s lifecycle, it becomes much harder to handle the odor. Using odor cover-ups is your best option in gaining extra protection.
During these weeks, the trichomes create the highest concentration of terpenes. Even when there are proper air circulation and ventilation, this time means the air has a high concentration of cannabis aroma.
Consequently, it’s best to beef up your odor management hacks by using odor absorbing gels.
Absorbing cover-ups work by clinging to odors and them replacing them with appealing scents.
To make it clear, absorbing gels literally mask the smell, but they can’t remove the odor in your marijuana grow space.
In fact, they are most suitable for improving the smell.
However, absorbing gels must not be placed inside a grow space because your weed plants will absorb the smell from the gel.
Once your weed plants absorb the new scent, their natural scent can be messed up. For that reason, use odor neutralizers moderately.
I suggest putting the gel on your carbon filter or exhaust hose.
Gels usually come with a lid, so you only have to open it whenever necessary.
Since odor neutralizers work best for only a couple of hours, you could say that this is an emergency option.
Can Air Purifiers Remove Odor in a Marijuana Grow Room?
Remember when I said that not even carbon filters can totally eliminate the stink from the air?
Well, air purifiers won’t have the power to do so.
We know how air purifiers work well in removing dust and allergies from the air circulating in our homes.
However, they aren’t potent enough to cover the strong smell of flowering marijuana
Should I Use an Ozone Generator to Mask the Smell in a Weed Grow Space?
Short answer – no. Back when indoor gardening applied old technology, ozone generators worked great in removing the smell of cannabis in a grow tent.
Unfortunately, it can only be used if there’s no humans or animals around. That’s how dangerous the machine can be.
Ozone is listed as a major indoor air contaminant, making it damaging to the lungs when inhaled.
Similarly, exposure to elevated levels of ozone may lead to lung disease.
While growing indoor marijuana brings you joy, remember that the aroma might not be pleasing to everyone, especially to your close proximity.
Using one of our suggested methods or combining some of them are investments worth taking. The units we’ve introduced are, in fact, essential to indoor gardening.
A temperature controlled and fully ventilated marijuana grow room equipped with a carbon filter exhaust and fans are able of removing almost 100% of the smell in your cannabis grow room.
Likewise, creating a good airflow across your growing space keep humidity levels and temperature stable.
Keep in mind that removing all air particulates results in unhealthy air in your grow room. Hence, the secret is to control the odor.
Combat that smell using these proven techniques and don’t let the odor stop you from producing quality marijuana in a grow space!
Based in Florida, Kimberly Sharpe has been a full-time web writer since 2006. She writes for numerous online sites and publications. She has published in USA Today and eBay. She has extensive experience in indoor gardening especially hydroponics and aquaponics. This includes equipment such as grow boxes, grow cabinets, grow lighting, and other hydroponic gardening topics.