10 Best Inline Fans For Your Grow Room

When growing indoors, your grow room ventilation is extremely important. Because most grow rooms or tents are enclosed and in tight quarters, without the right inline fan you’re looking at overheating your growing area and thus killing your plants.

Here are our top picks for inline fans as of right now, along with some crucial info on how to select one that best fits the size of your grow rooms or tents.

10 Best Inline Fan Reviews

1. Hydrofarm Active Air 6″ Inline Fan

Hydrofarm makes some of the best all-around hydroponics gear on the market, and their Active Air inline fan series are no departure. This 6” diameter fan is our top all-around choice, as 6” is the diameter most of us use in our ventilation systems. For the price and feature combination, it’s difficult to beat Hydrofarm.

Pros:

• Reputable, trusted brand in the industry
• High CFM for the price point
• Comes with all you need to mount

Cons:

• Louder than our premium 6” inline fan pick

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2. AC Infinity Cloudline S6

Made in America, AC Infinity’s Cloudline is definitely a top-of-the-line product with a price to match. Energy-efficient and super-quiet, it comes as a plug-and-play unit complete with a speed controller, all mounting gear, and the fan itself. Precise humidity and temperature sensors help you to set your fully-programmable controller for ideal conditions.

But as they say, everything has its price, and AC Infinity’s price point is significantly higher than other fans. It’s wholly worth the money spent. But if budget is an issue, this may be one to save up for.

Pros:

• Energy efficient
• Far quieter than other 6” fans
• Durable build quality

Cons:

• Price point is higher than average for a 6” duct fan

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3. AC Infinity Cloudline T6

Where the Cloudline S6 shines, this truly excels. On top of the speed controller, fan speed controller, and other features of the S6, this adds even more customization on its fully digital controls. A backup system keeps its memory sharp so it remembers the custom speed settings you input. A countdown system and alarm timer help you keep track of its status. There’s an eco-mode setting for when you’re trying to reduce your power usage. And even better, the T6 can share its smart controller with the older S6 model so they can both operate on the same upgraded programming. 

But there is one problem. The newer T6 model appears to have some occasional glitches in its alarm setup, and occasionally goes off for no reason. If you’re using the alarm to notify you of an increase in heat or humidity, you may find that an annoyance. As amazing as the updates are, the S6 is still a better buy for your money at least until they do a software upgrade for the T6.

Pros:

• Temperature and humidity controller included
• Alarm system on the controller
• Extremely quiet

Cons:

• Priciest on our list
• The alarm can sometimes trigger mistakenly

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4. Hydrofarm Active Air 8″ Inline Fan

A durable, ceramic-coated metal housing provides the framework upon which this sturdy fan is built. Like all of the Active Air series from Hydrofarm, it’s built with high-quality components and made to last. Low noise output makes this a refreshingly quiet way to keep the airflow cycling or to vent excess humidity.

None of the Hydrofarm systems have a speed controller included, but they’re available for a small additional fee. The only downside to this particular 8” model is that, as with many of the Hydrofarm fans, they’re meant to use rigid ducting. A flexible duct material is extremely difficult to connect.

Pros:

• Quiet operation
• Reliable manufacturer with a great reputation
• Comes with all installation components as a plug-and-play unit

Cons:

• No speed controls are included, although available at added cost
• Really should be used with non-flexible ducting

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5. AC Infinity Cloudline T8

I’m not going to claim that AC Infinity’s Cloudline is for everyone… but for those who want it, it’s perfection. The power cord for all of their Cloudline models is a good length, making it easy to install in grow rooms or tents. Truly made as inline duct fans, they’re easily connected to both flexible or rigid ductwork.

Like the other models, this one comes with all mounting equipment. However, they’ve changed from a smart controller to a humidity controller in the box, likely due to the T6 alarm issues.

Pros:

• Fan speed fully adjustable from slight breeze to high wind conditions
• Built in the United States, made to last

Cons:

• No longer comes with a smart controller – has a humidity controller instead
• Higher price point than other inline fans

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6. Vivosun 8″ Inline Fan

Are you just getting started and need a cheap inline fan for your operation? The Vivosun may not be one of the best inline fans on the market, but it’s a perfect starting point. Its inexpensive price makes it a great value for low-budget grow rooms, especially if you’re just looking for an air intake fan.

The drawbacks to a low price, however, may stall the proficient user. It’s got a short cord, which makes it a bit more difficult to connect up with ease. Carbon filtration is not an option, as it’s just not powerful enough to support it. And every so often, users have encountered poor motor operation upon testing a new unit – although, to their credit, they’re quick to replace faulty devices.

For someone who’s just starting out, this is a good way to go as you learn what works best in your growing environment.

Pros:

• Very reasonably priced
• All-metal construction
• Works well as an intake fan

Cons:

• Not designed for use with a carbon filter
• Short power cord
• Some users have experienced faulty motors out of the box

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7. Hydrofarm Active Air 10″ Inline Fan

Like the other Hydrofarm inline fans we’ve highlighted, this 10” model doesn’t come with a speed controller. However, it’s still a very reliable inline duct fan like the rest of its class. A rating of 760 CFM makes this a good choice for a larger space.

Pros:

• Reliable, respected manufacturer
• Mounting brackets included
• Good quality large fan for a reasonable price

Cons:

• Large diameter fan
• Does best with rigid ducting

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8. iPower 10″ Inline Duct Fan

The iPower line of fans is a good mid-range series of inline fans. It doesn’t come with all of the bells and whistles in one neat package, so if you’re looking for more than just a fan, this may disappoint. Extremely bare-bones, you’re likely to get a corded fan in this box and little else.

But having said that, the fan tends to have a reasonably decent lifespan and may be slightly easier for a beginner to install. It is noisier than most of the others on the list, but that may not be a drawback if you’re venting an outdoor greenhouse. My largest complaint with this fan is the composite blades and hub, as I prefer metal, and even that’s a small quibble.

Pros:

• Fluted at both ends for attaching ducting
• Can be used with carbon filtration
• Very reasonable price

Cons:

• Slightly noisier fan than others we’ve covered
• Fan blade and hub are composite rather than metal

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9. Hydrofarm Active Air 12″ Inline Fan

In essence, everything we’ve said about this series of fans applies for the 12” model except that it’s the largest and highest CFM rating of their fan line. Reliable, sturdy, ceramic-coated, and reasonably priced, they are a good place for most people to begin.

Pros:

• Well constructed, good longevity
• Manufacturer is respected and reliable
• Great price for a large-diameter fan

Cons:

• Requires rigid ducting for best use

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10. iPower 12″ Inline Duct Fan

The same benefits and negatives of the 10” iPower apply to the 12” fan. A bit noisier than most of the fans on our list, it’s still a decent product. It’s bare-bones straight out of the box, so don’t expect any fancy bells or whistles. But its fluted shape is easy to hook up to your system, and the price for this fan size is great.

Pros:

• Fluted shape makes it easy to hook into your duct system
• Carbon filters are available for this fan
• Reasonable price for its size

Cons:

• Composite fan blade/hub instead of metal
• Noisier than other makes of fan

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Selecting The Right Inline Fan

When growing indoors, you’re controlling the entire environment. Light, temperature, humidity…and ventilation. While it’s important to know what the best grow lights are for your garden, many growers forget about ventilation and how much it can affect a grow. Here are some factors to take into consideration when choosing inline fans.

Why Is It Important To Get Inline Fans?

Without proper grow room ventilation, you’re dooming your growing operation to failure before you even start. The cramped quarters and controlled environment of a grow tent or room require forethought and planning in order to achieve great yields.

Inline fans help exchange stale air out of the system, often passing through several layers of filtration along the way. For example, carbon odor filters are often linked to ventilation setups in order to keep unwanted smells from spreading around the environment.

What Is CFM And How Do I Calculate It?

One important measurement you’ll see on all fans is CFM, or Cubic Feet per Minute. This number refers to – you guessed it – the cubic feet per minute of air that the inline fan you’re considering is capable of exchanging out of a given area.

For example, imagine you have an 8’ x 4’ x 12’ room. This is 384 cubic feet of space (4 x 4 x 8). Let’s now imagine you wanted to exchange all of the air inside that room with fresh air once per minute. You might think you need a fan rated at 384 CFM, but you’d be wrong.

It’s always a good idea to multiply the cubic feet of your available space by at least 1.33 to account for any airflow drop due to any filters, etc. that are attached to your ventilation system.

Using that 1.33x multiplier, we get a required CFM number of ~510 to exchange the air in our example grow room once per minute. There are other factors to consider when calculating your air flow, like:

Your Grow Lights

The type of grow light you use will have a heavy impact on your ventilation needs. HID lights (HPS, MH) run hotter than others (LEDs, CFLs) and thus will heat your grow tent or room faster, meaning it needs more ventilation.

If you’re growing with HID lighting, add a 5% boost to your calculations for every light you’re operating inside your grow room. If your HID lights aren’t air-cooled, then you should adjust by 10-20% as there’s nothing cooling your lights down at all, meaning your ventilation system has to carry more weight.

Carbon or CO2 Filters

If you’re attaching filters to your ventilation system, it’s important to account for them in your calculations. Add at least 20% to your CFM calculation if you have filters attached to your ducting.

Average Temperatures

If you’re growing in a room that runs hotter than average straight out of the gate, you may want to boost your CFM calculations by at least 25% to be sure you’re ventilating enough. If you have a double whammy of high temperatures and high humidity, boost this number by about 40%.

Length of Your Ducting

The length of your ducting can influence how much power it’ll take to pull air out of your grow room. On top of that, if you have any twists and turns in your ventilation setup, those will also increase the CFM needed to exchange air at the correct rate.

What Diameter Inline Duct Fan Should I Get?

One factor that impacts your buying decision is the diameter of the fan. Wider fans will decrease the relative humidity of a grow room faster compared to smaller diameter ones.

Smaller diameter fans often have lower CFM ratings, but you’ll still need the right CFM for your space. After you’ve calculated your minimum CFM needs, select the smallest-diameter fan which can supply them. If you want to go a little higher than necessary, that’s fine, but remember that it might reduce your ambient humidity.

Other Factors To Consider

There are many other factors that will impact your buying decision when it comes to a fan. Here are some of the most common:

What is the Fan Being Used For?

There’s two basic uses for a fan: intake or exhaust. Intake is drawing air into the room, often through a carbon filter to remove pests or unwanted dust/pollen. Exhaust is venting air back out of the room.

Most setups rely more on exhaust vents than intake ones. That’s primarily because removing excess heat or humidity is far more common than needing to force air into a space. Our recommendations today focus on exhaust needs, although these fans can also be used for intake if desired.

Passive air intake handles the majority of growing needs. As you push air out of a room, more is being pulled in naturally through any crevices or gaps. Along with it comes any dust, pollen, or contaminants which might be suspended in the air.

Active intakes such as using a fan are usually an expense most growers don’t need unless they’re trying to prevent pests or pollution from impacting their plants. They can be useful, and they can be paired with added CO2, but it’s a fine-tuning of an issue which isn’t necessary for all but the most particular of growers.

Do You Need a Speed Adjuster?

Speed controllers can be nice, but they’re not universally required. If your fan is at your desired CFM range, you’ll never really need to adjust it.

If you’d prefer to get a higher-powered fan than you need for your space (perhaps to have room for future expansions), a speed controller can be a benefit. You can use the speed controller to reduce your fan’s CFM from its maximum level to the range of your current needs. Later, when you expand to match your fan’s capabilities, the speed controller won’t be as necessary.