Indoor growers benefit from a never-ending growing season, complete control over growing conditions, and the ease of growing indoors. This all sounds fantastic, but we always overlook the importance of growing room ventilation. The first attempts at indoor growing were fraught with difficulties. We had a fan set up that we figured would be enough to provide air circulation for my plants. We were mistaken. It takes more than a corner fan to ventilate a grow room properly.
If you continue to ask yourself questions like:
- Why is ventilation needed in grow rooms?
- How do you ventilate a grow room?
- How do you know the type of fan to get?
Don’t be panicked. We’ve made both of these errors (and more)… so that you don’t have to. As long as you understand the basics, grow room ventilation is very easy. So, let’s get started.
- Why Is It Essential to Ventilate Your Grow Room?
- Remove Excess Heat
- Humidity Control
- Prevent Pests and Diseases
- CO2 Management
- Control Wind Stress
- How to Ventilate Your Grow Room?
- Air Extractor Fan System
- Calculating Fan Strength
- Passive Intake vs Active Intake
- Frequently Answered Question: How to Ventilate Your Grow Room
- What type of fan do I Require?
- What size fan do I need for my Bulb?
- What Size fan do I need for my Room?
- How High should my intake Fan be?
- What Exactly is Negative Pressure?
- What Type of Ducting do I Require?
- What can I do to increase the efficiency of my ducting?
- Go Forth and Ventilate!
Why Is It Essential to Ventilate Your Grow Room?
So, why do grow rooms and grow tents require ventilation? As it turns out, there are several explanations. Plants were grown outside benefit from the cooling effects of light breezes, sunlight, evaporation, and precipitation. Indoors use fans to replace breezes and evaporation, grow lights to replace sunlight, and irrigation systems to replace precipitation. We sometimes miss that air circulates more naturally outside than it does in your grow space.
To keep the air in your grow room fresh, you’ll need both a fan and an air extraction device. This is why.
Remove Excess Heat
Heat is emitted by grow lights. It may not seem to be much, but a few degrees difference in temperature may mean the difference between a successful crop and a less successful crop. Many grow lights produce more heat than others, but they all generate enough heat to warrant ventilation.
Another factor that may lead to problems with indoor growing systems is humidity. Throughout the day, plants emit water vapor, which raises the humidity in your grow space. Uncontrolled humidity causes poor growing conditions and the growth of pests and diseases.
A good ventilation system often wicks away some of the water lost during transpiration, allowing your plants to absorb more water and pull up nutrients through their root systems, resulting in increased growth.
Prevent Pests and Diseases
Air circulation aids in the prevention of pests and diseases. Mold, powdery mildew, spider mites, and fungus gnats prefer moist, stagnant environments. Pests lay their eggs in moist topsoil, so keeping the surface layer of soil dry with a fan will delay their reproductive cycle, and a steady breeze makes it more difficult for them to establish themselves on your plants in the first place.
Plants need outside air for one simple reason: CO2. Plants consume CO2 as part of their nutrient cycle during the day. If your grow tent setup is sealed, the amount of CO2 in the room progressively decreases, restricting the growth of your plants. Ventilation brings in fresh air and CO2 from outside while removing old air from your grow space, resulting in increased growth and yields.
Control Wind Stress
The wind continually buffets outdoor plants. It strengthens the stems of the plants, which helps them when it comes time to bear fruit. Stronger plants produce and grow more efficiently than weaker plants, which can collapse under the weight of their yields.
So, what is the purpose of a grow room ventilation system? Let’s go over it again. A well-designed ventilation system:
- Reduces the likelihood of diseases such as mold and powdery mildew developing;
- Protects your plants from pests such as spider mites and fungus gnats;
- Allows you to monitor the temperature and humidity of your grow room;
- And strengthens the stems of your plants.
Consider the cost if those reasons aren’t enough to persuade you that you need a grow room ventilation system. The cost of erecting a grow tent is not easy. If you’re going to buy a grow tent or a grow space, you might as well do it right.
How to Ventilate Your Grow Room?
Place Oscillating Fans in the Grow Room
Remember that your grow room ventilation setup will need two types of fans as you learn how to vent a grow room.
- Air extractor fan system
- Oscillating fans
We’ll discuss the air extractor fan system later, but let’s concentrate on oscillating fans for now. These fans are inexpensive and powerful, which are two of my favorite characteristics of any device. They continuously blow air above, under, and around your plants, keeping the grow room cool and improving air circulation.
Oscillating fans are also simple to set up and carry around, so you can easily play with positioning to ensure you find the best spot for your fans. You want your oscillating fans to cover all areas of the growing space, which might necessitate purchasing a few fans, but you also don’t want them to aim directly at your plants. It can cause ‘wind burn’ and damage your plants (think gentle breeze vs. tropical storm).
Installing oscillating fans will help regulate the temperature and humidity in your grow space, but fans alone will not suffice. To keep the air in your grow room or grow tent fresh, you’ll need an air extractor fan device.
Air Extractor Fan System
An air extractor fan device cycles old air out and brings in the fresh air your plants need to survive. Your extractor fan system should refill the air in your grow room every minute or every three to five minutes at the very least. This means you must choose the appropriate size fan for the job.
One of the best choices I’ve ever made was to combine a grow tent set up with a grow tent ventilation setup. Before investing in a grow tent setup, take a moment to learn about grow tent ventilation. Since you won’t have to maneuver around existing plants or change your system, installing a ventilation system in your grow tent during setup is the best time.
Calculating Fan Strength
Calculating the necessary fan strength necessitates some math, but it is relatively easy. CFM, or cubic feet per minute, is the unit of measurement for fans. To calculate the CFM needed, you must first know:
- The sizes of your grow tent or grow space
- The quality of exhaust
Multiply the length, width, and height of your grow room to get the total volume. It is the cubic footage of your home. Keep this number handy. Then we’ll multiply that by the efficiency decrease.
This efficiency varies depending on the age and makes of the filter and the length of the duct between the fan and filter, among a plethora of other factors. You can multiply the volume of your space by 25% at the very least, but here’s a simple rule of thumb: if you have a long duct path, multiply it by 3, and if you have a short path, multiply it by 2.
Your formula should look something like this:
- CFM = Room volume × Efficiency decrease
For e.g., if your room’s volume is 320 cubic feet and you have a short duct, multiply this number by 2.
- 320 × 2 = 640
Now that you know your CFM, look for a higher number of fans.
Passive Intake vs Active Intake
There are two methods for bringing air into your grow room: passive intake and active intake. Passive intake is based on negative pressure and passive airflow. There is a fan blowing air out, but no fan blowing air in for this grow room ventilation system. Instead, you have an intake hole that passively allows new air to enter due to pressure differences between the inside and outside of the room.
To make a passive device work, make your intake hole three to four times larger than your exhaust hole. This will keep your fan from overworking and will aid in the proper suction of your ventilation system. You may also have multiple passive intake holes.
Active intake systems use a fan to draw air into your grow space continuously. This means that one fan is blowing air out and another is blowing air in. The size of the intake hole is less important in this system, so if your intake hole is the same size as your exhaust hole, you can consider using an active intake system.
Frequently Answered Question: How to Ventilate Your Grow Room
Before we wrap up this guide, let’s go over some frequently asked questions.
What type of fan do I Require?
Choosing a fan for your grow room ventilation is not an easy task. There are several options available. To begin, you’ll need an in-line duct fan with a CFM rating greater than your grow room’s measured CFM.
If you’ve determined the fan’s specifications, you must choose a make and model. Fans vary in price, so read a lot of product reviews to ensure you’re getting the best fan for your money. Check to see if the filter is included with the fan or if you must purchase it separately.
What size fan do I need for my Bulb?
The size of your bulb is one aspect that can help you narrow down your fan quest. The majority of fans are available in 4-inch, 6-inch, and 8-inch diameters. Because of the size of the light hood opening, you can get at least a 6-inch diameter fan. This opening is usually 6 inches wide, but measure to be sure.
What Size fan do I need for my Room?
To determine how large a fan you need for your bed, use the formula we discussed earlier to measure the CFM of your room. This number will assist you in determining the fan range that will fit best with your setup.
You can also buy some inexpensive oscillating fans to help regulate temperature and monitor airflow in your grow space.
How High should my intake Fan be?
The size of your intake fan is determined by two factors: the type of device you use and the size of your exhaust fan. If you use a passive intake method, the solution is straightforward. You do not need an intake fan. If you have an active intake system, choose a fan that is the same size as your exhaust fan.
Learn more about How Long Do LED Grow Lights Last in Reality?
What Exactly is Negative Pressure?
If the pressure inside your grow room is lower than the pressure outside, you have negative pressure. This theory is used during passive intake, as the negative pressure in the room draws clean air in from outside through the intake hole.
Are you perplexed? Consider negative pressure to be a trip under the water in a plywood vessel. Water rushes into the box when you fall because the pressure inside the box is less than the pressure of the water outside. Assume that the water flowing in is clean air and that the water leaving bubbles is polluted air. When you sink, pat yourself on the back for knowing negative pressure.
What Type of Ducting do I Require?
Most grow systems benefit from flexible aluminum ducting. It is inexpensive and simple to build, but you can also use insulated aluminum ducting or a heavy-duty duct depending on your tastes and budget.
The most important consideration when choosing ducting is scale. Smaller ducts provide more airflow resistance, as do more twists in the duct and the length of the duct, so airflow decreases as it travels further.
Read more about the Benefits of an Outdoor Mist Fan
What can I do to increase the efficiency of my ducting?
If you have flexible aluminum ducting, the first thing you can do is smooth out the wrinkles. This will boost the efficiency of your ducting by increasing the airflow. You may also try to reroute the duct to make fewer turns and, if necessary, shorten the length of the duct system.
Go Forth and Ventilate!
We hope you enjoyed this grow room ventilation system tutorial. Choosing the best ventilation system for your grow room can be difficult, which is why we believe it is essential for indoor growers to understand how ventilation systems function and the advantages of grow room ventilation systems. If you know the fundamentals, you will be far better at choosing the best system for your service.