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How Often Should I Run Exhaust Fan In a Grow Tent?

Have you just bought a grow tent? Well, you have made a very economical and beneficial decision! Either it is for your passion or the growth of your business.

Grow tents are almost the perfect antidote for the problems caused by indoor plantations. Like other technologies, it can be used for the fabrication of outstanding indoor plant growth.

 However, if not used properly, it has the potential to cause havoc in your indoor plantation.

Besides answering the fundamental question of the topic, this article explains why an ideal running time of exhaust is essential for any grow tent.

Ideal running time for an exhaust fan

To calculate the ideal duration of which an exhaust fan should be turned on inside a grow tent, we must first measure the grow tent. Different grow tents require different amounts of ventilation.

The analysis of a grow tent should be done in cubic feet. After we have taken the proper measurement of the room, we simply need to divide it by three to get the ideal exhaust fan running time inside a grow tent.

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The unit for running an exhaust fan is CFM. This stands for cubic feet per minute. This lets us know how much air should be exchanged in the specific grow tent we are measuring.

CFM depends on two things. Firstly, it depends on the size of the grow tent and secondly on the size of the exhaust. The influence of the size of the exhaust fan is so less that it is usually neglected.

Mathematical explanation:

In almost every grow tent, an exhaust should refresh the air inside after every three minutes. To optimize the exhaust according to the ideal exhaust time, we simply have to divide the total volume of our grow tent by three.


Suppose that you possess a grow tent, which is about 720 cubic feet in size.

If that is the case, you simply have to divide 720 by three. By doing this, you get your CFM, which is the unit of the ideal time for running an exhaust. In this case, the CFM that is calculated equals 240.

720 / 3 = 240 CFM


This is the ideal time of how much an exhaust fan should run inside a grow tent of a specific volume. However, it is always advised to use an exhaust with more CFM.

This is mainly because inside a grow tent, many other factors begin to play a role, which I have discussed below. These factors affect ventilation in a grow tent.

Therefore, using an exhaust with slightly higher CFM is preferred as it helps in maintaining that perfect ventilation your plants are literally dying for.


Grow tents are 21st-century greenhouses. For people who find greenhouses not economical enough, grow tents serve as the perfect solution for them. These box-shaped canvas enclosure can give plants their ideal conditions for growth.

Like all living things, plants also need a specific environment for their perfect growth. Therefore, we must use grow tents properly. It is almost crucial for the healthy growth of your plants.

In horticulture, proper ventilation is as essential for plants as breathing is to humans. It refers to the exchange of stale air inside the grow tent with that of the fresh air.

If a tent is not adequately ventilated, it will result in either of the two conditions:

  • Either you are going to see the slow growth of your plants
  • or, your plants will have stunted growth

Therefore, ventilation is the key to having a perfect grow tent. Let’s see why ventilation is essential.

Why is proper ventilation necessary?

There are three fundamental reasons why without ventilation, plants experience slow or stunted growth. They are as follows:


Humidity must be controlled in indoor plantations. All professional urban farmers know how rain can affect plant growth. The optimum humidity level for healthy plant growth is about 45% to 75%.

If the humidity in your plants is about 20 to 40 percent, It must be taken control of. Otherwise, you are at significant risk of losing your plants. Ventilation can come to your rescue if you are stuck in this situation.


All of us know that the kitchen of plants is the process of photosynthesis. The stock for that kitchen is Carbon Dioxide. New carbon dioxide can only come from proper ventilation.

Without adequate ventilation, the amount of carbon dioxide inside a grow tent would become stale, and therefore, it will become destructive instead of constructive for the plants.


In every grow tent, light is used for the proper growth of the plants. This is crucial for plants as it takes up the role of sunlight. Also, like sunlight, grow light produces heat, which increases the temperature inside the grow tent.

This increase in temperature inside a grow tent must be taken care of. Every plant has its optimum temperature. Using proper ventilation can help us provide that plant with the ideal temperature for its healthy growth.

Additional Information


Exhausts are the most critical component in any ventilation system. It helps in removing heat, bringing fresh doses of CO2 and in maintaining the humidity inside the ventilation system.

It must be installed high up in the tent. Since hot air rises while the cold air being denser settles down. We need to remove the heat from grow tents. Therefore, exhausts are always installed at the top.

Fresh air intake:

The second most important piece of equipment is the sharp air intake. Make sure that it is connected precisely to the opposite side of the exhaust.

This will help in untangling the wires, which may overlap while installing the ventilations. The blocking of air due to the overlapping of hoses causes severe troublesome obstruction.

Amount of plants:

Make sure to not overcrowed the plants inside the grow tent. These types of acts cause the plants not to develop to their full extent and hence injure their growth.

If you want healthy and maximum growth of your plants, make sure that you do not overcrowd the grow tent.


Urban farmers must be familiar with the idea of minimalism. The secret to genius in the indoor plantation is simplicity, not complexity.

Therefore, instead of focusing on the number of plants that you grow inside a grow tent, you ought to focus on the quality of plants that you produce.

Try to be a master of building one kind of plant instead of being a jack at increasing all types of them.

Grow Room ACs:

Most people are not familiar with a modern ventilation system for grow tents. The popular modern way of ventilation is now the use of ACs.

They, apart from being slightly uneconomical, give urban farmers reasonable control of their ventilation system. They can be used in a wide range of climates.

And also, it can be placed anywhere inside the grow tent. However, it can cause damage to plants if set too close to them.

Why is this all so important?

The ventilation system that you will use in a grow tent must never be ignored. A proper ventilation system is as essential to your plants as air is to you.

The information that we have shared with you is the nectar of three years of experience of people who have adopted indoor plantation as their profession.

A pro tip for you is to always be consistent in checking your ventilation system and reporting any problem to an electrician. You must also have basic knowledge of other necessary parts that are used in a grow tent. These are air humidifiers, grow lights and the other basic requirements that different plants have for themselves.

The first and foremost thing required for the healthy growth of your plants in a grow tent is how you set up your ventilation system.

Ventilation systems are the most fundamental necessity for letting plants thrive. Most people generally focus on what plants to grow instead of concentrating on how to improve their growth.

Urban farmers must learn about the ideal conditions for the growth of their plants. If you are reading this, you are probably on the right way to urban farming. Therefore, kudos to your effort and happy farming!

The information that this article shares with you covers the most frequently asked question which modern urban farmers ask when they are basically in their novice days. It throws light at almost all parts of the ventilation system in a grow tent.