How to set up grow tent ventilation

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cannabis fan
May 16, 2021
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Installing an efficient cannabis setup relies on a few key factors. Chiefly amongst these is providing your weed plants with good airflow by installing sufficient grow tent ventilation.

Keep reading this guide to find out what you’ll need for good grow tent ventilation and how to put it together. We also discuss different types of layouts and answer the frequently asked questions. Let’s get started.

Why is grow tent ventilation important?

Cultivators that plant their marijuana seeds outdoors enjoy all that nature has to offer. Wind, precipitation, and sunshine each have a part to play in the lifecycle of a cannabis plant. When growers decide to move their operation to an indoor grow tent setup, it’s up to them to provide these vital ingredients

To create a fresh and healthy airflow, you need to install an air extractor and a fan to create this much-needed ventilation for a grow tent. By doing this, you’re assisting your cannabis plant with the following factors.

Prevent pests and diseases

Stale air is usually a recipe for disaster. It creates a perfect environment for diseases like mildew and mold to thrive, destroying all of your hard work. What’s more, the increasing humidity will welcome the presence of gnats and spider mites, further degrading the health of your crop.

By installing a grow tent ventilation kit, you can avoid these conditions, allowing your marijuana seeds to mature into a potent harvest. Fans don’t just keep the humidity down; they also dry the top layer of soil, making it hard for pests to lay their eggs.

Perfect temperature and heat

Indoor lights, just like the sunshine, are essential to a cannabis plant’s life cycle. Both of these light sources also heat the surrounding air, increasing the overall temperature. Good grow tent ventilation acts in a similar way to wind, regulating the temperature of the air.

While some lights emit less heat than conventional bulbs, they can still burn your crop. Fans stop this from occurring, allowing your grow tent ventilation setup to control the heat.

Control of CO2 levels

During the day, your marijuana plants breathe in CO2 and release oxygen. This phenomenon swops around at night time, modeling a human respiratory system. When your indoor setup is sealed, the levels of these vital gases decrease.

Grow tent ventilation pulls in fresh new air and releases the old, allowing your ganja plants to stay healthy and strong.

Plant and stem strength

As your weed seeds grow, the weight of its dense buds can cause the stems to bend and even break. While trellis nets can help with this heavy load, your crop must be strong enough to do most of the work. 

Sufficient grow tent ventilation mimics a gentle breeze, forcing your cannabis plant’s stems to strengthen in the wind.

Wind stress avoidance

While wind is crucial to the health of your cannabis plants, too much of it can create further issues. By giving the wind from your fans a way to escape, you avoid over-stressing your crop.

You’ll need to make sure your grow tent ventilation fans aren’t blowing too strong, as this will lower the plant’s yield. Look out for wind-burned leaves, resembling a claw, as a tale-tale sign of too much airflow.

Smell control

Another benefit of installing grow tent ventilation is the mitigation of pungent aromas taking over your home. The smell of maturing cannabis can sometimes overpower the senses, making it hard to hide your crop from passers-by.

Ventilation allows you to control these odors, expelling them discreetly and maintaining that fresh smell in your house.

Sizing your grow tent ventilation system

Regardless of whether you plan on installing a big or small grow tent ventilation setup, you’ll need the right sized fans. While every space is different, you can rely on a simple calculator to put you on the right path.

You need to calculate the volume of your grow room by multiplying its width, height, and length. For example, let’s say you have a 3x5x4ft greenhouse. 

Length(4ft) x width(3ft) x height(5ft) = 60ft cubed.

Now that you have the volume, you can search for exhaust fans that provide at least 60 CFM(cubic feet per minute). By doing this, you ensure your grow tent ventilation replaces all the air surrounding your marijuana plants.

In order to ensure you have enough space in your greenhouse, there are various setups that you can use. Below are the most popular methods available, shown by a handy grow tent ventilation diagram.

grow tent ventilation diagram
Grow tent ventilation diagram

Choosing the right fan for the exhaust system

Regardless of the size of your indoor setup, it’s essential to install an exhaust system. By doing this, you give the old air a way to escape and create room for new, fresh gases to enter.

Below are the three key factors to consider when choosing the best exhaust system for your grow tent ventilation.

  • Figure out the cubic area of your grow tent.
  • Consider how efficient the path of your system is.
  • Pick either a booster or an inline exhaust fan.

Once you’ve calculated the volume of your greenhouse, you can determine the amount of power your extractor fan must produce.

The next aspect to take into account is how efficient your tubing is. An inefficient path has lots of bends and takes time to expel gases due to its long length. While an efficient setup consists of short, straight pipes, allowing the air to exit faster.

Finally, there are two types of fans available. Inline fans have the highest CFM output, making them the optimal choice. Booster fans help to increase the CFM rating of your grow tent slightly. It’s recommended to use these in conjunction with inline fans rather than on their own.

Four steps to set up your grow tent ventilation system

Learning how to grow marijuana indoors can become a stressful operation without the correct knowledge. Don’t let that stop you because we’ve got your back. 

We’ve put together a step-by-step grow tent ventilation guide, allowing you to create the best possible climate in your greenhouse.

Step1 – Place an oscillating fan

The first step to set up your grow tent ventilation involves placing some oscillating fans inside your greenhouse. They help circulate the air around your weed plants, helping to avoid things like mold and maintain the temperature. 

You don’t want these fans blowing directly on your cannabis, as this can cause damage. Instead, try to get the air moving around the room by placing two or more fans in opposite corners.

Step 2 – Install an air extractor

The next step involves installing a system to extract the old, dirty air. It also helps maintain the humidity levels in your tent, creating a beneficial climate for your cannabis plants. As we’ve mentioned, you’ll need to use an exhaust fan with enough strength to replace the air every minute

You’ll also need to decide on the best layout of this system for your room. Consider using one of the popular grow tent ventilation setups that we showed diagrams for earlier.

Step 3 – Use a passive or active intake

Decide whether your greenhouse will need a passive or active intake system. This decision depends heavily on the size of your greenhouse. 

Smaller grow rooms work well with passive intakes, allowing the air to filter naturally as a result of negative pressure. These holes must be at least three times bigger than the exhaust opening to function correctly.

An active intake system relies on an additional fan to suck the outside air into your tent. You’ll effectively have one fan blowing air in while the other directs the air out. Always ensure your intake fan produces less power than your exhaust to maintain the negative pressure.

Step 4 – Consider using a CO2 Injection

If you plan on having a fully sealed grow room, injecting more CO2 into it can help with transpiration. For this system to work correctly, you’ll need to keep the CO2 levels very high. You must make sure this gas doesn’t leak, as it can cause potential harm to you and anyone else nearby. 

You’ll also need to use stronger lights if you add CO2 injections to your grow tent ventilation system. Regular fluorescent bulbs won’t work, so you’ll need to use either LEDs or HPS lights.

Grow tent ventilation FAQs

This section looks at the most common questions when learning how to set up your grow tent ventilation correctly.

How big does my intake fan need to be?

While a smaller grow tent ventilation setup doesn’t need an intake fan, they become important when you increase the scale of your operation. As a rule of thumb, your intake fan must always produce less power than your exhaust fan.

How big of a fan do I need for my bulb?

Fans generally come in three sizes, namely four, six, and eight-inch diameters. Your best bet is to stick with the six-inch fans, regardless of how small your greenhouse. This ensures your lights don’t create too much heat.

What is negative pressure?

Negative pressure basically means the pressure outside of your grow tent is greater than the pressure inside. It’s an important principle to understand as it assists passive air intake. The negative pressure inside your room pulls in fresh air while pushing the old, dirty air out.

What type of ducting is best for you?

When it comes to ducting, it all depends on your budget. Aluminum piping is easy to set up and is an affordable option used by many growers. There are also insulated and heavy-duty versions, but these are best for colder climates or industrial-scale greenhouses.

Remember that the smaller the opening of the ducts, the more resistance the airflow will experience.

How can I control the noise of tent ventilation?

To mitigate the loud noises from your grow tent ventilation fans, you can insulate them with cardboard. Another way to do this is by installing a muffler on the vents. If your budget allows, consider using insulated ducts and purchasing a speed controller for your fan.