Growing cannabis indoors is the best way to grow because it gives you total control of the conditions, meaning that you can have many grow seasons per year instead of just one. Your plants are able to grow healthy and big, and your buds will be tasty and potent, all because you are able to give your cannabis exactly what it needs in order to flourish.
One of the many things you are in charge of when growing indoors is air circulation. Outside, this is a naturally occurring gentle breeze or wind. Inside, we have to recreate this using inline fans.
How do inline fans help you grow your cannabis?
Your plants need to be well ventilated in order to provide them with the CO2 they need to grow, to keep humidity levels stable, and to prevent rot and mildew. Ventilation is also important in temperature regulation. Your grow lights will also give off heat, so keeping the air around your plants flowing constantly helps prevent them from overheating and drying out. Your plants need fresh air every 1 – 3 minutes, and inline fans are a great way to provide this.
How to decide on the correct fan for your grow room
First off, you need to assess the size of your grow tent or grow space. You need to know the measurements in order to calculate the cubic feet per meter (CFM) rating that your new fan will need to have to be effective in your grow room. This is the amount of air that a fan can move per minute in cubic feet. So if a fan has a CFM rating of 200, it can move 200 cubic feet of air per minute.
Here is a handy formula to help you find the best fan for your grow space:
Length x width x height (in feet) of your grow room multiplied by 1.25 (125%)
The reason we multiply by 125% is because the extra 25% gives us some leeway to account for things that might slow down air flow, such as carbon filters.
The higher the CFM rating, the more expensive the fan will be. If you aren’t looking to spend lots, then what you could do is find a fan that will move the required amount of air every three minutes instead of every minute. You can do this by completing the above calculation, and then dividing the final number by 3. If you don’t live in an especially warm climate, then this will be enough to sustain your plants.
The next thing to be aware of is the actual size of the fan. Inline fans come in all shapes and sizes, so you need to make sure it can fit comfortably in your grow space. The most common inline fan sizes are 4, 6 and 8 inches. If you are not sure which is best for you, we recommend the 6 inch. If it turns out not to be the right size, you can easily buy a converter to increase or decrease the size of the openings.
Factor in your grow lights
As well as light, grow lights also give off a lot of heat. Some lights will emit more heat than others, so it is important to know what sort of grow light you have and how hot it will run before buying a circulation fan. For example, HID lights put out a lot more heat than LEDs, and so will need a fan that can circulate more air per minute in order to dissipate the extra heat.
If you are using HID grow lights, it is recommended to add 5% to the above calculation for every air-cooled HID lamp, and 10-15% for every non-air-cooled HID lamp. If you are unsure, err on the side of caution and get a fan with a slightly higher CFM rating. This way you can be sure your plants are getting all the fresh air they need.
With this new fan knowledge, have a look through our reviews below to find the fan that fits your grow room requirements.
Can Fan Max Mixed Flow Inline Fan
This small, lightweight fan only comes in size 6 inches and has a CFM rating of 334, making it perfect for a medium sized grow space. It is energy efficient, saving you on utility bills, and has an airtight housing so it doesn’t take up lots of space. It also comes with a 5-year warranty.
The Can Fan Max is popular with intermediate growers, as it can handle a decent grow space with a good number of plants in it without breaking the bank.
Can Fan Pro Series Inline Fans
These fans come in three sizes with different CFM ratings: the 6 inch fan with a 420 CFM rating, the 8 inch fan with a 863 CFM rating, and the 16 inch fan with a 2343 CFM rating. This Pro Series of fans operate more quietly and are more efficient than the Can Fan Max (above). They are built to last, with their housing made of fiberglass reinforced plastic compounds that meet CSA and UL standards. The Can Fan Pro Series fans all come with a 120V power cord, and each fan has three different speed settings.
The durable, high standard materials and the high CFM ratings mean that these fans don’t come cheap. However, this makes them long lasting, and their efficiency makes them cost effective in the long run. Can Fan Pro offers some of the biggest and best inline fans on the market, which is perfect for the serious bigtime grower.
Apollo Horticulture Inline Fans
The Apollo Horticulture fans also come in a range of sizes and CFM ratings: the 4 inch fan with a 190 CFM rating, the 6 inch fan with a 440 CFM rating, and the 8 inch fan with a 740 CFM rating.
These fans are built using steel coated in a rust resistant powder paint, which means they will last even in high humidity conditions. They also come with a built-in speed adjuster, giving you more precise control over the air flow in your grow room.
VenTech VT Inline Duct Fan with Carbon Filters
This fan is a very high quality product – it is not just used by growers, but by hospitals too! Its powder paint coated steel frame is built for efficiency and stability, and includes a Virgin Charcoal Carbon Filter which helps hide odour. This is perfect for anyone looking to grow discreetly.
This model is 6 inches in size, with a CFM rating of 440. This rating is slightly lower that the other fans of the same size in this review, but the included carbon filter makes up for that. The fan also comes with a one-year warranty and a mount, so you can hang it wherever you need to.
The VenTech inline fan is great for small scale, discreet growers looking for high quality and a simple, easy setup.
Vortex Powerfan VTX
The Vortex Powerfan is one of the quietest inline fans on the market because it uses a sound muffling gauge steel casing. It is also humidity proof, with an anti-rust hammertone powder coat epoxy finish.
This line offers five different models: the 4 inch fan with a 172 CFM rating, the 6 inch fan with a 497 CFM rating, the 8 inch fan with a 747 CFM rating, the 10 inch fan with a 790 CFM rating, and finally the huge 12 inch fan with a 1140 CFM rating.
Each model comes with a factory installed 120V power cord, and the extended collar and lip of these fans, as well as the included mounting brackets, make them easy to hang and hook up to air ducts.
This fan has a permanently lubricated motor, making the Vortex Powerfan a highly durable product. On top of this, it comes with a huge 10-year warranty, so you know it is a fan built to last!
Active Air Inline Fans
Active Air, like Vortex Powerfan, also offer five different sized models: the 4 inch fan with a 165 CFM rating, the 6 inch fan with a 400 CFM rating, the 8 inch fan with a 720 CFM rating, the 10 inch fan with a 760 CFM rating, and the 12 inch fan with a 969 CFM rating. All of these fans have a rust preventing ceramic coating, thermally protected AC motors, and high-quality moulded impellers.
All Active Air fans are made using UL rated components, ensuring high quality, quiet and durable performance, so you know you are getting the best for your money.
Hurricane Incline Fans
Hurricane fans also come in five different sizes: the 4 inch fan with a 171 CFM rating, the 6 inch fan with a 435 CFM rating, the 8 inch fan with a 745 CFM rating, the 10 inch fan with a 780 CFM rating, and the 12 inch fan with a 1060 CFM rating. Each fan comes with its own mounting brackets and an 8 foot 120V power cord.
Hurricane make their fans with UL rated components and mechanisms, making them quiet and efficient. They also have a durable powder coated finish which ensures that the fans are rust resistant and are capable of working in high humidity environments.
iPower GLFANXINLINE6 High CFM Duct Line Fans
iPower provide four different sizes of inline fans: the 4 inch fan with a 190 CFM rating, the 6 inch fan with a 442 CFM rating, 8 inch fan with a 745 CFM rating, the 10 inch fan with a 862 CFM rating, and the 12 inch fan with a 1060 CFM rating. The fans come with strain relief, a completely wired junction box, and a 5 foot UL rated power cord.
iPower inline fans are made to run smoothly and quietly with their permanently lubricated bearings, and would be ideal for growers with lots of long tracks of ducting.
Rule 240 Inline Fan
This is a small fan, only measuring 4 inches, but it has a CFM rating of 235 which is impressive for its size. The motor is protected by a sealed motor shaft, and the exterior is protected from moisture by a nickel-plated casing.
This Rule 240 inline fan is perfect for growers with a small grow space who don’t want to spend huge amounts on an air circulation fan.
The Yescom HO is also a great choice for growers on a budget, with three sizes for your specific grow space needs: the 4 inch fan with a 175 CFM rating, the 6 inch fan with a 353 CFM rating, and the 8 inch fan with a 720 CFM rating. Each fan features an extended lip and collar, and they come with a horizontal/vertical mounting set to make set up easier.
This fan runs quietly due to its backward curved impeller with vibration free operation, and all of the components are UL certified, so you know the fan is made of high quality, durable materials. This would make a great purchase for a small time grower with a small to medium budget.
Inline fans are the best way to keep the air circulating around your indoor grow space. Without proper air circulation, your plants run the risk of growing mould or mildew, as well as suffering from increased temperature and humidity levels. Outdoors, plants get all the fresh air they need, so it is important to provide the same level of air circulation when growing indoors.
Hopefully the above inline fan reviews have given you some insight as to what is currently on the market, and you can make the right purchase based on your grow space requirements. Remember, if you are not entirely sure which size to get, err on the side of caution. It is better to have an overly ventilated grow space than an under-ventilated grow space.