Carbon Filter Setup Guide: How to Set Up Carbon Filter in Grow Tent & Outside

When you are setting up a carbon filter in a grow tent, proper ventilation is imperative - you already know that. But, did you know that part of that is ensuring that your carbon filter setup is optimal? 

In this article, we’re going to talk about how to set up a carbon filter in a grow tent as well as how to set up a carbon filter outside a grow tent and the advantages and disadvantages of each approach. First - why is your carbon filter setup so important?

The Importance of Perfecting Your Carbon Filter Setup

Setting up a carbon filter in a grow tent is important both because it is effective in controlling the odor that comes from your plants as they grow and in eliminating pathogens that may harm your plants. That means that you need to set the conditions for your carbon filter to persevere.  

While a carbon filter will come with a predefined lifespan, you can take steps to make your carbon filter last. You also want to ensure that you have the best carbon filter for your grow room that you can get so that your setup is effective and the air in your grow room is properly treated.

Two Ways You Can Go About Carbon Filter Setup

There are two common carbon filter setup methods for odor control: the “scrubbing” method and the “exhaust” method.

The "Scrubbing" Method 

A setup using the “scrubbing” method circulates air in your grow space continuously through the filter. When using this method, the air is passed through the filter multiple times. This allows you to use a faster airflow rate. It is used in a ‘closed loop’ system, where the ‘fresh air’ is provided by CO2 generators.

The "Exhaust" Method 

With this method, the polluted air is pulled through the filter once and expelled outside. When exhausting air outside, it is recommended to have the filter suspended over the canopy of your grow space to capture odor more efficiently. 

Since this method requires the filter to eliminate odor and pollutants in one pass, it is recommended to use a slower fan speed for such applications. This is a straightforward method that is common for most grow rooms.

Pros & Cons of the Scrubbing Method

The advantage of the scrubbing method is that it allows for better control over odor while keeping the grow space environment sealed from the outside environment. Even if the filter did not eliminate all odors on the first pass due to air not having enough contact time with carbon, the lingering smell will be removed on the subsequent passes. 

In addition, this method will allow growers to maximize growth and yield by using CO2 supplementation, since the air is not being exhausted outside, the added CO2 will remain in the grow space. In other words, the scrubbing method is the best way to control odor in sealed climate grow setups. 

Pros & Cons of the Exhaust Method

The primary advantage of the exhaust method is that it will not only cleanse the air of odors but will also create negative pressure which will help to bring in fresh air from the “lung” room or outside and lower the inside temperature and humidity, since as air heated by the grow lights will be exhausted outside. In other words, you can not only scrub air but also manage the temperature and humidity inside the tent with the same fan connected to the carbon filter on one end of the duct line and the exhaust vent on the other end of the duct.

Because it requires an ‘open loop’ setup, it is drawing air from the outside, which means that your air is subject to the surrounding climate which in some locations could be harsh for the cultivated plants. In addition, the air has only one chance to go through the carbon filter before being expelled, meaning that you have to ensure that the air is not moving too fast as it needs enough contact time with the carbon to ensure that odors are absorbed by carbon on the first pass. As the carbon gets saturated with impurities over time, the speed will have to be readjusted to lower levels to allow even longer contact time with the carbon. 

Which Method is Right for You?

The method you choose will depend on the style of your growing, whether you use supplemental CO2 to enhance growth, the space available, your budget, and your personal preference. Some growers prefer the closed-loop scrubbing method due to the control that it gives them over environmental conditions. This requires more specialized equipment, which will up your costs but the opportunity to higher yields per plant. But ultimately, there is no ‘wrong’ or ‘right’ answer for the best method of setting up a carbon filter in grow tent. 

How to Set Up Carbon Filter in Grow Tent: Step by Step

In this section, we’ll cover how to set up a carbon filter in a grow tent, giving you a quick walkthrough that applies regardless of the method you choose. The setup of your carbon filter will take place at the same time you install your ventilation system.  

1. The carbon filter should be installed in close proximity to the source of odor allowing it to capture as much odor as possible before the odors get a chance to spread across a larger area. We recommend having the filter suspended from the reinforcement bars of the grow tent by the tent’s ceiling with the duct opening of the filter pointed towards the top exhaust vent of the tent. 
2. Either secure an inline fan directly to the carbon filter or set up ducting to attach the two (If you need more specifics, check out our discussion on installing your inline fan). In the case of TerraBloom’s EC fans and carbon filters, we have ensured that our EC inline duct fans fit flush with the flange of the carbon filter, so using a duct is not mandatory in such a case. However, if you want to have some distance between the fan and the filter, then the best way to connect them together is by using our lightproof flexible air ducting which comes with two fastening duct clamps in each set.  
3. Place one cloth pre-filter over the carbon filter’s mesh portion to prevent large dust and debris particles from entering the filter’s carbon bed. Using pre-filters and washing them when they get dirty prolongs the useful life of the carbon filter and prevents clogging. Each TerraBloom carbon filter comes with 2 pre-filters that serve the same purpose, please use one pre-filter at a time and use the second one as a replacement when the dirty pre-filters are being washed. Air dry your pre-filters to avoid shrinking. 
4. Hang the carbon filter and inline fan assembly in the desired location.  
5. (Exhaust method only) Run ducting from the end of the inline fan to an exhaust vent, and secure both ends of the ductwork.
6. Adjust your fan’s speed setting to accommodate the method that you are using. The scrubbing method will use higher fan speeds, while the exhaust method will use slower speeds.
7. Run the power cord to the fan to the nearest power source. 

How to Set Up Carbon Filter Outside Grow Tent: Step by Step

If you have a small grow tent and try to maximize every inch of the horizontal and vertical space inside the tent, it is acceptable to position the filter on top of the grow tent (if the filter is smaller in size) or on the floor immediately next to the tent. In such case, you will have to use the duct to connect the fan to the filter and ensure that all connections are air-tight (you are moving untreated smelly air over the duct) and the tent has a consistent negative pressure so that the air will not be escaping through the zippers and tent seams. In the setups with the carbon filter placed outside of the grow tent, you will be moving air from the tent and blowing it into the carbon filter.  

There are two methods of how to set up a carbon filter outside grow tent - with the fan in the tent, or with the fan as part of the carbon filter setup.

1. Set up your carbon filter near your desired location. Make sure that its flange (where the air goes inside the filter) is pointing up.
2. (Fan outside the tent) Either secure an inline fan directly on top of the flange of the carbon filter or set up ducting to attach the two.
3. Secure the carbon filter assembly and duct it to the vent hole of the grow tent so that the air will be pulled from the tent via the negative pressure created by the fans and then pushed through the carbon bed of the filter and out.
4. Because in the external carbon filters set up you’ll have the air moving in reverse to the traditional inside tent installation method, the use of the cloth pre-filter will not prevent debris or large particles of dust and soil from getting into the filter’s carbon bed. Such a setup will be more prone to clogging which in turn will reduce the life of the carbon filter. To prevent clogging, we recommend using a simple intake air filtering mechanism to be installed on the intake side of the duct fan, which is connected to the filter. The easiest way is to place an intake safety grille on the flange of the fan and to put a hairnet, which is used in restaurants, commercial grow facilities, etc over the intake safety grille. The safety grille is required to prevent the hair net from being pulled into the fan and damaging the fan’s blades, do not attempt to put a hairnet over the fan’s intake flange without the safety grille in place as it will inevitably be pulled into the fan, breaking its blades and causing a safety hazard if it jams the motor. 

Other Tips for Setting Up Carbon Filter in Grow Tent or Outside

If the description of how to set up a carbon filter outside a grow tent intrigues you, you should know that the recommended setup for a carbon filter is to have it inside the grow tent. Here are some tips on how to set up your carbon filter for any application. 

Set Up Your Filter Outside (Limited Space) 

Having your carbon filter inside is superior to an outside setup - however, it may not always be feasible or desirable. Putting a carbon filter outside your tent may be preferable if you have limited space, or if your filter is too big for your tent. The drawbacks to this include reduced effectiveness for your filter, and the requirement for higher fan speeds, which make more noise. If you do not have a choice, ensure that you get the best inline duct fan that you can.

Make Sure You Have Good Ductwork

Whether inside or outside, try to keep your ducting as straight as possible, and choose the shortest routes so that your fans are more effective. There are different types of ducting, and you should also give thought to how you choose the ducting for your grow room.

Optimize the Rest of Your Climate

To ensure a longer lifespan for your carbon filter and to preserve odor absorption, your filter must be used in environments with a relative humidity of less than 80% at all times. The carbon inside the filter can adsorb water content from the air in the same way as it absorbs odors and  VOCs. By not controlling the humidity inside your grow you are reducing the useful life of the filter and exposing your plants to bud rot and mold/mildew. Indica plants with larger and heavier flowers are especially more prone to such infestations which can completely ruin your harvest and tend to outbreak closer to the end of the flower cycle when the fruits of your labor grow big and retain more moisture inside. 

What’s even worse, humidity spikes can lead to clumping of carbon inside the filter's bed which will turn into air pockets once the carbon is down. These air pockets can and will allow untreated odorous air to pass through without proper scrubbing. Your ventilation system is the number one way of controlling humidity, but you can have even more control with a dehumidifier.

Get Quality Ventilation Components

The best ventilation setups use the best components. Not all carbon filters are created equal, so if you are setting up a carbon filter in a grow tent and want to take some of the guesswork out of finding the right one, Terrabloom can help you find a quality cannabis carbon filter. 

Whether you set up that carbon filter in your tent or out of it, and regardless of what method you use to process your air, your inline exhaust fan will be vital to your setup. Terrabloom also offers quality commercial inline exhaust fans to get you going.

Make Sure You’ve Sized Equipment Correctly

While equipment of different sizes can be adapted to work together, it is best that all your equipment remain the same size. Terrabloom has 4 inch carbon filters, 6 inch carbon filters, 8 inch carbon filters, 10 inch carbon filters, and 12 inch carbon filters; whatever the size of your equipment, we can accommodate you. We can help you match up your inline fan, and get the right size for your intake fan.  

Final Thoughts on Carbon Filter Setup

The methods for how to set up a carbon filter in a grow tent and how to set up a carbon filter outside a grow tent both require a little bit of planning. While the exhaust method is the most common way of treating the air in the grow room, the scrubbing method offers an attractive alternative that, with the right equipment, can give you more control. 

Make sure that you use quality components and keep your climate optimized for the best growing experience. Shop at Terrabloom, where we can help you find the carbon filters and inline fans that you need for your grow room. You can check out our website to see what we offer or visit our blog for more ideas on how to set up your growing space.