When starting an indoor grow room, there are a lot of things to consider in order to make it a successful hobby or even a living.
If you’re growing your crop indoors through the use of a grow tent, then you have to really strategize how your grow tent ventilation setup will be rolled out.
A grow tent’s ventilation setup is sometimes easily ignored, because growers tend to focus on things like what plants to grow and how would they water and fertilize their plants.
The thing is, ventilation is one of the most important keys to let your plants thrive.
If you don’t know where to begin just yet, we got you covered!
Here, We've complied a quick and easy guide about why it’s important to ensure proper ventilation setup in your grow room or grow tent, the things you’ll need, and easiest and most efficient way to setup your extraction system!
Why Your Grow Tent’s Ventilation Matters?
As mentioned, having a good ventilation setup matters as this is important to your plant’s survival and even the quality of your crops.
Here we list the reasons why ventilation is important in this kind of setting. After all, this will feel like an easier task if you understand its importance to the best of your knowledge.
Helps you control the humidity level in your grow room
If you’ve previously worked on an indoor grow setup and had crops or plants that grew not the way you want them to, then it might have been the uncontrolled humidity in your grow room.
....This has something to do with the quality of the plants you will have.
Another reason why controlling the humidity level in your grow room is important is because poor ventilation may lead to diseases or pest that you don’t want your plants to get.
Avoids pests and plant diseases
Pests and diseases are bound to happen with poor ventilation. Most common diseases that your plants could get would be mold, mildew, spider mites, fungus, etc. These are pests and diseases that thrive in humid areas.
This could be a big problem as some of those are sometimes hard to detect. When you do, it could be already too late to save your crops.
You’ll just regret not planning on your ventilation system once this happens to you!
Keeping the CO2 level just right
Photosynthesis is everything when it comes to your plants’ growth. If you leave your grow tent closed without ventilation, your plants won’t have enough carbon dioxide. Without CO2, your plants will just wilt and eventually die.
Your ventilation setup is what will help your plants get the right amount CO2 that they need. With enough CO2, your plants or crops will grow healthy.
Photosynthesis will be compromised if your grow room won’t have enough CO2.
To lessen heat and wind stress
Heat is unavoidable in an indoor grow room setup because you’ll be using grow lights to serve as your indoor sunlight.
Whether you’ll use ordinary grow lights or the ones that are LEDs, all of those will produce heat.
If there will be no ventilation system in your grow tent, your plants will wilt and die from heat. Constant air circulation will lessen the intensity of heat in your grow tent.
This is the same when it comes to wind stress. Your plants will become stronger if they only get enough air.
The Basic Ventilation Setup
The basic setup is also known as the passive ventilation setup. This is only composed of extractor fans or exhaust fans to many and regular electric fans or oscillating fans.
It’s basic, but this is already good enough for small indoor spaces, most especially if your grow room is in a humid environment.
Basically, the passive setup extracts humidity from your grow space and lets a cool air come spread through the use of regular fans.
The Active Ventilation Setup
The active setup also has what the basic setup requires, extractor and oscillating fans. The main difference is that an active setup also consists of an intake fan.
The intake fan helps your system bring in fresh air in your grow tent or room.
However, if your grow space isn’t really that big, you don’t need to go for an active setup.
The active setup is only best for grow spaces that can accommodate large intake holes.
What to Get for Your Grow Tent’s Ventilation Setup: Calculating Fan Requirements For Incoming Air
setup Oscillating Fans
This is the easiest and cheapest way to ventilate your indoor grow area. It’s easy to purchase this in supermarkets or even online.
Aside from that, it’s not expensive to run even if you keep it on the whole day.
This is great for small grow rooms, like a grow tent. In fact, for a small grow tent, a single fan alone could already serve as its ventilating system.
If your grow space is bigger, you can simply get additional fans.
What Fan Size Should You Get?
There are different fan sizes available that you can get. Fans usually range from four to even 12 inches in diameters. It’s best to at least get a 6-inch fan in diameters. This should be good enough to ventilate air properly in your grow tent.
If you’re only thinking of getting a 4-inch fan or you’re simply left with no other choice, then consider getting at least two of these.
Where should the fans be placed?
Here are some tips you could follow to know where to exactly place the fans in your grow tent:
- In a grow tent, it’s ideal to have at least two medium-sized fans so that the air will really have a good circulation in your grow tent. You can just place one fan above your plants and another on the ground.
- Again, oscillating fans are best to use in your grow tent so that the fans won’t focus on just one area or particular plants. Remember that wind stress can cause your plants to grow weak or even worse, not grow at all.
- To know if you have enough fans for your grow area, have a feel of how even the breeze is in your space. Make sure that when your fans are turning their heads, all areas are covered. If there’s one specific space that doesn’t seem to get any breeze, adjust your fans accordingly.
This will help a lot if you have a medium-sized grow area. Now, don’t just install an exhaust fan without having a fan or more. Exhaust fans will only help regulate the humidity in your grow area. Your plants will still need a source of air.
For extractor or exhaust fans, here is a guide that could help you determine the fan power you’ll need:
Determine how big your grow room is
It’s best to know the volume of your grow room. The volume is simply the size of your grow room in a three-dimensional space.
All you really have to do is to multiply the length, width and height of your grow space to come up with the volume size.
If the size of your grow room is 6 feet long, 8 feet wide, and 15 feet tall, then below is how you compute for your grow space’s volume:
6 x 8 x 15 = 720 cubic feet
How do you calculate CFM for a grow room?
CFM means the amount of air moved. This lets you measure how much air should be exchanged in your grow space. CFM stands for cubic feet per minute and it’s the unit used for this type of measurement.
If you’re wondering how often your exhaust fan should be exchanging air, it should ideally exchange air at least once every three minutes.
To calculate for the ideal exhaust that your grow area should have, simply divide the volume of your grow space into three.
720 cubic feet / three minutes = 240 CFM
This means that if you’re to purchase an exhaust fan for your grow room that is 720 cubic feet in volume, your exhaust fan should at least be at 240 CFM.
That’s how you calculate your exhaust fan needs for your grow room. This is how to know the minimum requirement of your space.
It’s always better to get an exhaust fan with a higher CFM because there are other factors to consider, like the grow lights that produce heat, the temperature or humidity in the room, and the number of plants that you have.
Where to Place an Exhaust Fan?
Now that you know how important it is to lessen the humidity in your grow room, having an exhaust fan now seems something necessary, right?
If you only have a medium-sized grow room or tent, then one exhaust would already do the job.
What’s important now is to know where to place your exhaust fan for it to be very efficient. Hot air actually goes upward or always rises.
That said, exhaust fans should be placed somewhere above your plants or in the high area of your tent.
Putting an exhaust fan above the grow tent will create a vacuum effect. It means that it will suck the humidity and pull the cool breeze upwards to improve the air circulation in your grow area.
This is a popular modern way to ventilate your indoor grow room. ACs work best in a medium to big-sized grow rooms. An air conditioner is efficient when it comes to removing heat and it also gives the growers good control of the ventilation setup in their grow room.
It’s best to get air conditioners that are used for low ambient cooling like this black + decker portable air conditioner unit which come in 8,000 to 14,000 BTU sizes. It means that even if it’s freezing outside, your air conditioning unit can still give just the right amount of cooling in your grow space.
The measurement or unit used when it comes to sizing the air conditioner that will suit your grow room is called BTU or the British Thermal Unit.
How many BTU do I need for my room?
Just like how it is with fans, the size of the air conditioning unit you’ll need will depend on the size of your grow room in cubic feet or volume.
While it’s true that other factors such as the lighting and the number of plants in the room should also be considered, basing on the volume of your grow room will let you know the minimum BTU you’ll need for your air conditioner.
Here is a guide to help you know what to get depending on the size of your grow space:
Room Volume in Cubic Feet
1 – 1200
1200 – 1600
1600 - 2000
2000 - 2400
2400 - 2800
2800 - 3200
3200 - 3600
If you have a bigger room that’s no longer mentioned above, every one thousand BTU equates to about 400 cubic feet of grow space.
Where to Place the Air Conditioning Unit in Your Grow Space
There’s really nothing complicated about where to place an air conditioning unit in your grow space or tent. What you really want is for the air conditioning unit to distribute the cool breeze around your grow area.
A lot of growers place their air conditioning unit in a large grow space on the ceiling so that it could directly blow cool breeze towards their crops or plants, but if you have a small air conditioning unit and a small grow space, then simply place you unit on the ground.
Just make sure that it is not too near your plants to avoid wind stress and to let the cool air spread in your grow space evenly.
Factors like the air conditioning tubing should also be considered. It’s bet to have your air conditioning placed somewhere where it could dispose water easily – this means you should place it near an exit.
If you plan on getting an active ventilation setup, then you’ll need to get an intake fan. Again, the purpose of having this is to let fresh air come in your grow space.
It’s very easy to know the ideal size of intake fan that you should get for your grow room.
After you’ve figured out the ideal exhaust or extractor fan that you’ll need in your grow space, you can just get an intake fan that’s identical with it.
Basically, the CFM of your extractor fans should be the same with your intake fans.
Where to Place an Intake Fan in Your Grow Space?
Intake fans basically brings cool air from the outside. It’s always best to have them placed on the ground so that more cool air will be moving upward instead of humidity.
Place the intake fan where cool breeze is likely to pass from the outside of your tent.
CO2 Burners or Injection
This isn’t really required when it comes to setting up your own indoor grow tent. CO2 burners could help enrich the carbon dioxide in your grow tent, but do take note that these also produce heat.
If you choose to include this in your ventilation system, then a higher BTU or CFU for your air conditioning unit or fans is a must.
CO2 burners or injectors should only be used in a closed grow space or tent. This is to ensure that your plants only get enough CO2.
Aside from that, the right amount of CO2 on plants is already considered dangerous for humans.
Also, you need to keep in mind that it’s only best to add CO2 burners in your setup if the situation really calls for it and your setup without CO2 burners isn’t working out.
Adding CO2 burners in your setup could be quite pricey, so there’s really no need to add one on your setup if you’re already satisfied with your output.
Where to Place CO2 Burners or Injectors in Your Grow Space and How to Use It
A lot of growers place their CO2 generators on the ceiling to ensure that it will be evenly spread among the plants that you have in your grow space. It isn’t necessary to turn this device on the whole day.
The PPM level you should maintain in your grow area is 1500. Grow lights are already considered on this level.
During the night, you can turn your CO2 generators off. If lighting or photosynthesis is controlled in your grow tent, this just means that if you turn your grow lights off, the CO2 injectors should also be turned off.
It’s best to turn your injectors off at least an hour before you turn the lights off.
Again, it’s important to stress out that the use of Co2 injectors require knowledge as this could be dangerous to humans when misused.
If you’re just starting out with using this device, you should get a PPM monitor, (I usually use Hydrofarm Autopilot Desktop CO2 Monitor) to make sure that the level of CO2 in your grow area will always be controlled.
Your grow tent’s ventilation setup should never be ignored. It should be something that you should sit down and plan on, so that your indoor gardening experience would be fun rather than problematic.
If it’s your first time to do this on your own, you may go through a trial and error phase, so that you can eventually get the hang of it.
The information we’ve shared with you should already help you avoid encountering problems that have something to do with your grow room’s ventilation.
Aside from what’s mentioned above, you also need to have the basic knowledge of how everything in an indoor grow room setup works, and this includes the grow lights, air humidifiers, exhaust fans, and the requirements of the plants that you are trying to grow.
All of these will help you have a successful indoor grow room or tent.
Lindsey Hyland grew up in Arizona where she attended University of Arizona’s Controlled Environment Agriculture. She has supplemented her formal education by working on various organic farms, including spending a semester abroad in India.
Growing and/or raising just about anything gets her excited. She is especially passionate about environmental justice and low-tech, sustainable ways to better run small-scale farms and homesteads. Lindsey started Urban Organic Yield to discuss gardening tips and tactics.