How much CFM do I need for my grow tent? 2020 Updated

If you plan on having a closed environment (e.g., grow room, grow tent, etc...) then you need to properly ventilate your growing environment to ensure your plants perform at their best. Proper ventilation helps regulate humidity, exhaust the warm air that your grow lights and electronic equipment are producing, and provide relatively carbon-rich air for your plants to breathe.

Why is it necessary to ventilate my grow room?

There are two main reasons to keep fresh air flowing through your garden:
1) to evacuate excess heat generated by lamps, pumps, etc.
2) to provide fresh air (i.e. oxygen and carbon dioxide) to your plants while removing the excess humidity they generate.

A high-wattage indoor grow lights in a sealed, unventilated room will quickly raise the ambient temperature to 100+ degrees Fahrenheit.  At these temperatures, plants grow slowly (if at all) and can succumb to heat stress, or may simply die.  Barring issues caused by temperature, without proper ventilation, your plants will eventually use up the available carbon dioxide and oxygen, and increase the humidity in the grow tent for weeds (via transpiration) to unacceptable levels, leading to suffocation. A single properly placed and connected ventilation fan can easily prevent these issues.

Many websites give a blanket rule-of-thumb for CFM calculation that fails to take into account the uniqueness of each growing room.

Each inline duct fan has a rating that tells you how many cubic feet of air per minute (CFM) it will move. When dealing with above average temperatures you will want your fan to exchange the grow room air 3-5 times in one minute, so for a room that is 40 cubic feet, a fan that is capable of moving 120-200 cfm (cubic feet per minute) is recommended. If you only want to replace depleted levels of co2 and are growing in a closet using fluorescents, one room change per five minutes (divide room size by 5) will be adequate.

To calculate your room size, multiply Width by Length by Height, this will give you the CFM rating required for one room change per minute.

it’s a 10x10x7 feet tent that you’re dealing with. So, the fan size will be-

Fan Size= (10 feet x 10 feet x 7 feet)/1 Minute= 700 CFM

Placing Fans

Ideally you’d like a nice breeze surrounding the main canopy, which means you want air blowing above and under the plants.

Don’t point a strong fan directly at a plant, because too much wind can start to damage the leaves and stems.

After placing fans, check around the grow area to make sure that all parts get a slight breeze. If you feel stagnant air or a lack or breeze, you may want to adjust your fans.

Small oscillating fans are great for the grow space since they’re cheap and can be used to provide a nice gentle breeze to a relatively wide area without blowing on any one part too long.

HURRICANE Inline Duct Fan for Grow Room



With an estimation of 10 inches and a power rating of 780 CFM, this is something else that is ideal for enormous scale applications. In the event that you are a business cultivator, instead of an ace, this is a perfect decision.

The inline fan is made of steel with powder covering. With this, you can make sure that it will shock like sturdiness. Mounting regions are beginning at now combined into the unit, likewise as far-reaching direction. With the last referenced, the establishment should be possible in only a couple of minutes.

Finally, there is a five-year guarantee offered by the maker, which should beginning at now ensure that the quality will be difficult to compose.