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Setting Up Ventilation in Your Grow Tent

Setting Up Ventilation in Your Grow Tent


Airflow is an extremely important part of growing a healthy plant. Proper airflow replaces CO2 and removes O2 from the immediate area around your plants, and helps build structural resilience in stems. Without proper airflow, your plants will struggle to get enough compounds to photosynthesize light. We recommend having two different ways of producing airflow: first is through a ventilation system and second is through simple oscillating fans. The oscillating fans are to help circulate the air immediately around the plant, while the ventilation brings in new, fresh air. Here we will discuss arranging the ventilation system.

When first arranging your grow tent you might run into the question of how to set up your ventilation system properly. The best way to think about ventilation is to first consider air pressure.

Simply, there are three states of air pressure that can be considered for your tent:

-Positive air pressure: This is when air is forcibly pushed into your tent and can passively leave your tent.

-Negative air pressure: This is when air is forcibly pulled out of your tent and can passively enter your tent.

-No air pressure: This is when air can passively enter and exit your tent without any assistance.


With this in mind, we can visualize the organization of our set ups:


Positive air pressure:


Air is being forced into the tent. We usually like to organize our ducting and fan at the top of the tent and leave a flap or ventilation port open at the bottom. When you set up your fan, it should be facing towards the inside of your tent:

(The arrow should face the tent)


Make sure the fan is pushing air into the tent.


Once air is being pushed into the tent, you are creating a positive airflow. This is a very standard way of setting up the tent and guarantees you’ll always have fresh air for your plants. One problem you might run into is that your tent will bulge from this increased air pressure. To relieve this effect, simply open more flaps to release the pressure, or you may need a less powerful fan.


Negative air pressure:

Unsurprisingly, negative airflow is the opposite of positive airflow, so you’ll be taking air out of your tent and allowing air to passively flow into your tent. This is the preferred set up method if you plan to use a filter to remove smells. A filter set up can look like either one of these set ups:


Here we can see that the fan is pulling air from inside of the tent through the filter. It does not matter whether the filter is at the beginning of the ducting or the end, you will end up with the same effect. The purpose is, of course, to push or pull the air through the filter. Of course, you can also organize a negative airflow without the filter.

One thing you may notice is that your tent is getting “sucked” inwards with this set up. Simply open more ventilation ports to reduce the issue, or if it persists it may be that your fan is too powerful for the size of tent you have.


No Air Pressure:


This is the simplest set up to organize: just open the ventilation ports of your tent and that’s it! However, you will never grow healthy plants without constant circulation of carbon dioxide so this set up is not recommended if you are trying to grow heathy, productive plants.


You’ll notice that in each of these set ups you will need to have ventilation ports open in your tent. This is actually quite important for plants, since you will have a difficult time replacing the fresh air if there are no auxiliary ports open in your tent.


What you’ll need:

At the very basic level, you will need the following:

-A ventilation fan that can move an appropriate amount of air for your tent, called “Cubic Feet per Minute” or CFM. Your fan will be working two jobs: circulating new air and cooling the space. You can calculate the CFM required by finding the cubic feet of the grow space and dividing that number by five, since the air in the space should be replaced every five minutes. There are good CFM calculators online like this one from Hydrotek Hydroponics.

-Ducting, to connect your fan to the outside world.

-A filter, to remove any odors, if necessary.

-Some way to hang the fan from the tent roof, such as these adjustable hangers.


We also sell whole grow tent kits where we have already matched the right fan with the right tent, such as this kit here.


When in doubt, feel free to reach out to us via phone or email and we can help walk you through setting up your tent.


Happy growing!


  • C-Monster

    How do you properly vent a small 2 in 1 tent? Without placing a filter between the plants and the light?

  • Nathan

    Do you have a diagram for ventilating your 48×60 2 in 1 tent?

  • Bruce

    Can you use inline air for fresh air and have filter and fan inside for exhaust?

  • George

    I just purchased a 36 × 36 × 72 tent. And
    VIVOSUN Air Filtration Kit: 4 Inch 203 CFM Inline Fan with Speed Controller, 4’’ Carbon Filter and 8 Feet of Ducting Combo
    I was hoping I bought the right combination I just did it without checking. Thanks again in advanced

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