Ventilation: A Quick Primer


Proper ventilation is crucial for controlling temperature and humidity. The best practice is to have an appropriately-sized inline duct fan to match your space. Having the right sized fan will help move the right volume of air – not so much that it causes your tent fabric to bulge or suck in; not too little to make no difference. We’ve put together a chart to help you match your fan size with your tent and we have a little graphic to help you consider how to set up ventilation.

How to set up your ventilation:

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.

This image shows what positive airflow looks like: air being pushed into your tent and passively let out from the ventilation ports at the bottom.

For negative air pressure, you’ll want a set up that looks like this:

You can see there are benefits and drawbacks to both but if you plan to use a carbon filter you’ll need to set up a negative air pressure system like the image above. Your filter can be either inside or outside the tent as you prefer.

What size fan do you need for your grow space?

The question isn’t too difficult to answer. We measure airflow with “cubic feet per minute” or CFM. Your fan’s CFM should match your tent size, with a little extra power to offset any equipment that causes increases in heat (lights) or obstructions (bends in ducting). Here is our chart that matches CFM requirements to our various tent sizes:

We hope this helps you set up and figure out what size fan you need for your grow space! Best of luck, we’re here to help!


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