Grow Room Setup: Should I Grow Weed In A Sealed or Vented Room?

GRow tent

After selecting the perfect indoor grow space, you’ll need to determine whether you are going to run a sealed or vented room (or tent, as the case may be). This is major distinction and will drastically impact how your grow room is set up and what equipment you’ll need to purchase.

Before I get into the specifics of each type of grow room setup, we need to make sure you understand the basic environmental factors cannabis needs to grow. When we refer to environmental controls as they relate to growing weed, we’re talking specifically about temperature, humidity, and CO2 levels. Regardless of the type of room (vented or sealed), each of these parameters needs to be kept within a specific range.

Fresh Air Exchange

As the name indicates, this style of indoor grow room relies on constantly exchanging the air in the room so that the cannabis plants are always being supplied with adequate CO2 levels. If the air weren’t being exchanged every minute or two, the plants would use all the CO2 available in the air and growth would come to a screeching halt – this is why its so important to select an extraction fan that’s powerful enough to exchange the entirety of the air in your grow space each minute or two.

The extraction fan’s air moving capability is measured in cubic feet per minute or CFM. You’ll want to select an extraction fan with a CFM that meets or exceeds your room dimensions – meaning if your room measures 10x10x8 (800 cubic feet), you’ll need an extraction fan that is rated to roughly 800 CFM. The reason I recommend purchasing a fan rated to a volume that’s equal or larger to your room is because of the inefficiencies caused by ducting, lights, and a carbon filter – these will result in the need to add 20-50%+ to your room’s volume calculation.

Extraction fans are typically connected to a carbon filter that prevents that skunky smell from leaving your grow room. For smaller grow rooms and tents, you’ll only need an extraction fan and can rely on a passive air intake. Alternatively, larger rooms will benefit from an active air intake; however, it’s very important that your extraction fan be rated at a higher CFM than your intake fan to retain negative air pressure in the room. This negative air pressure ensures that all of your grow room air passes through the carbon filter before leaving the room or tent.

Pros

Cheaper: Most rooms/tents only need an extraction fan – no other equipment

Natural: Mimics the natural CO2 levels found in nature

Cons

Less Control: Unless you have extensive automated controls in place, using an extraction fan results in less control over environmental factors like humidity because the air is constantly being replaced.

Sealed Rooms

As you may have guessed, a sealed room is just that – a sealed room that doesn’t allow air in or out. That being said, the same air that continuously circulates throughout the grow room must be conditioned with A/C, supplemented with CO2, and (de)humidified as needed – remember, each of these environmental factors must be kept in a specific range. In order to ensure the those environmental factors are within the desired range, sealed rooms rely on a master environmental controller monitors the room's actual levels and triggers the equipment to make adjustments as necessary. As you can see, this requires significantly more equipment than running a vented room.

Pros

More Control: Simply put, this results in the ability to cultivate higher quality cannabis and more of it. Keep in mind that environmental factors and genetics are the two biggest inputs that determine the quality and yield of your harvest. You can now run the 'perfect' environment 24/7.

Cons

Cost: Given the large up-front setup cost associated with a sealed room, they are typically reserved for larger operations. While it is possible to run a 'sealed tent' most people don't as it is simply not worth it.