Looking for the quietest inline fan for grow tent or grow room setups? We’ll help you choose the best quiet inline duct fan (with reviews), including the 4 inch, 6 inch, 8 inch, and 10 inch inline fan sizes most commonly used by weed growers at home.
We will also discuss how to set up silent grow tent fans to reduce noise as much as possible, reducing motor hum with a speed controller, and tips for inline fan noise reduction including how to create an inline fan silencer box. Or learn more about grow tent fans for air circulation.
Finding the quietest inline fan for grow tent or grow room use
Below is a list of the best silent grow tent fans for grow tent or grow room usage.
Finding the quietest inline fan takes a little detective work since all fan sellers claim they’re quiet and efficient. Noise levels from grow tent fans are measured in decibels (dB) or All manufacturers will tell you that they’re quiet. But you’ll need to compare decibels in order to find the quietest inline fan. Below is a list of the best silent grow tent fans for grow tent or grow room usage.
4 inch inline fan quiet models
Here are a few options for the quietest 4″ inline fan for grow tent or grow room usage. These 4 inch fans work well in 2×2, 2×4, 3×3, and 4×4 grow tents.
AC Infinity Cloudline S4 Inline Duct Fan 4″ with Speed Control ($89)
Best silent inline duct fan: 4″
The AC Infinity Cloudline S4 inline duct fan with speed controller is a ventilation exhaust fan for grow rooms and grow tents.
The S4 delivers 205 CFM of airflow at a sound level of only 28 dBA. The noise level is reduced when the fan is running at lower speeds. It is the quietest inline fan in the 4 inch size, and it delivers good airflow at a reasonable price.
The AC Infinity Cloudline S4 is more than enough for grow tents sized 4×4 feet or smaller (assuming you don’t have an overly long vent run or lots of right turns or elbows which reduce airflow). They also make an upgraded model that has a built-in humidity controller.
It has an 8-speed manual controller so you can reduce airflow and noise levels. It uses 21 watts of power at full speed. It comes with a corded AC power adapter and all necessary mounting hardware.
Mars Hydro 4 Inch Inline Duct Fan ($89)
The Mars Hydro 4 inch inline duct fan delivers 205 CFM at only 28 dB. It has a durable plastic fan housing and blades with dual ball bearings for extremely low noise levels.
This nearly silent inline fan uses a variable speed controller for easy fan speed adjustment. You can further reduce the sound levels by turning down the speed. It weighs only 4 pounds for easy mounting in your tent or room. Also available with a thermostat controller or as a set including the fan and a carbon filter.
This can has removable duct ends with locking tabs for quick removal and easy maintenance. The cord length is 4.9 feet. This 4 inch model is one of the best quiet inline fan models that Mars Hydro makes.
TerraBloom ECMF-100 Quiet 4 Inch Inline Duct Fan ($69)
The TerraBloom ECMF-1000 4″ inline duct fan features brushless EC Motor and dual jet type blades to deliver a 141 CFM airflow rate using just 21 Watts at max speed. It’s very quiet at only 18 decibels. But this low sound level is achieved by a reduced airflow compared to some other 4″ inline fan models listed on this page.
This nearly silent inline duct fan would work well in a 3×3 or 2×4 grow tent or smaller. This duct fan probably isn’t enough to use with a carbon filter in a 4×4 grow tent or larger unless you have a really short duct run with no more than one right angle turn.
Remember, it’s always better to get a slightly more powerful fan than you think you’ll need and run it at a lower speed to minimize sound.
This fan includes a variable speed controller that can reduce fan speeds without creating background noise or motor hum at low speeds. This model also lets you upgrade to the TerraBloom wireless remote control (Model: ECMF-WR) and intelligent thermostat speed controller (Model: SC-ECMF) if needed.
It is built with a rust-resistant aluminum housing that resists rust, protects the motor & blades from accidental damage. It is HVI Certified, Energy Star Listed, and comes with a 2 year warranty.
Vivosun 4 Inch Inline Duct Fan ($52)
Lowest priced 4 inch quiet inline duct fan
The Vivosun 4 inch inline duct fan delivers air flow of 190 CFM at a quiet 31 dB noise level. The fan is made of plastic and uses 59 watts of power at full speed. It has a basic speed controller attached.
Vivosun also makes a 4″ fan and filter kit which is a great value since it comes with both the inline fan and 14″ long carbon filter that eliminates the smell of stinky weed plants from your exhaust.
We’ve used several Vivosun 4″ inline fans over the years. The noise level isn’t as high as some of their competitors. But they tend to last a while in our experience. And given the lower price point, it’s still a good 4 inch quiet inline fan that’s only 3 dB louder than the AC Infinity or Mars Hydro options (although admittedly not as powerful). The carbon filters work pretty well too.
The low price point makes these an attractive fan for new growers who need to buy all of their equipment at once and are trying to limit startup costs. But this is more an entry-level duct fan. Growers looking for better long term performance may want to shell out a few dollars more to get an AC Infinity.
6 inch inline fan quiet models
Running a 6 inch inline fan at lower speeds is much quieter than running a 4 inch fan at full speed, both in terms of noise from the fan and the sound of blowing air. Consider getting a slightly larger fan than you’ll need and run it on lower speeds if you’re looking for a nearly silent grow tent fan setup.
6″ inline fans work well in 4×4 or 5×5 grow tents. This is the minimum size you’ll need if you’re looking to attach it to air-cooled lighting fixtures.
AC Infinity Cloudline S6 Inline Fan ($109)
Best silent inline duct fan: 6 inch
The AC Infinity Cloudline S6 is a 6 inch inline fan that delivers a powerful 402 CFM of airflow at only 32 dBA. This is the most powerful of the “quiet” 6 inch inline duct fan models.
This fan comes with a built-in 8-speed manual speed controller so you can fine-tune airflow. It uses an Electronically Commutated (EC) motor which runs at 38 watts that is controlled using precise electronic pulses and smart programming. The EC motor is also twice as energy-efficient and can save up to 40% in energy costs.
This fan is perfect for midsize grow tent and grow room setups such as 4×4, 5×5, or to air-cool a 6″ lighting hood. It is more powerful than other 6-inch duct fans, letting you run it at a lower speed to further reduce sound levels. You can use a single Cloudline speed controller to power multiple sizes of AC Infinity fans, allowing you to use this 6″ fan as an exhaust fan paired with a 4″ intake fan.
AC infinity also offers a similar 6″ fan with a temperature and humidity controller to help you regulate conditions in your grow room or tent.
Spider Farmer 6 Inch Inline Duct Fan ($99)
The Spider Farmer 6″ inline duct fan produces 32 dB of sound while delivering 350 CFM of air movement. It uses a mixed flow design combined with a EC motor and plastic impellers.
The built-in fan controller lets you set your speed precisely and has an 8.2 ft long controller cord for easy setup outside of the tent. It uses 50 watts of power.
There are several different kits available that include this fan, including a model with a thermometer and humidity controller with a carbon filter.
At $99 the price of the Spider Farmer makes it a decent choice as a six inch inline fan quiet enough for grow rooms in the 4×4 feet or 5×5 feet range.
TerraBloom 6″ Silenced Inline Duct Fan ECMF-150-S ($199)
TerraBloom’s 6″ silenced grow tent fans have a 2″ thick layer of sound-insulation foam placed inside a steel body with four vibration-reducing suspension springs inside.
The unit runs from 31-50 dBA depending on fan speed setting. This ECMF-S series fans offer a 10-15 dBa of noise output reduction vs. the company’s regular, non-insulated TerraBloom ECMF fans of matching size. That level of noise output gets perceived as 50% quieter to human ears.
But it’s still not as silent as the more powerful AC Infinity 6″ fan described above, despite being much more expensive.
This quiet inline fan has a brushless EC Motor and dual jet-type blades. It has an airflow rating of 288 CFM and uses 36 watts at max speed. It is HVI Certified and meets the ENERGY STAR Most Efficient 2021 Criteria.
The included speed controller lets you choose any speed from 0 to 100% with no hum at low speeds. This fan can also be upgraded to a wireless remote control (Model: ECMF-WR) or an intelligent thermostat speed controller with temperature programming (Model: SC-ECMF). This flexibility lets you tailor the fan setup to the needs of your cannabis grow. It comes with a two year warranty.
TerraBloom ECMF-150 Quiet 6″ Inline Duct Fan ($99)
Best value: 6 inch quiet inline duct fan
The TerraBloom ECMF-150 6″ fan isn’t the quietest inline duct fan TerraBloom offers. That distinction goes to their “silenced” 6-inch fan model ECMF-150-S described above. But at half the price and a sound level of only 31 dB, it’s a great value.
One disparity to point out about the sound level claims in the TerraBloom product descriptions. This ECMF-150 fan model claims to be 31 dB. Their “silenced” ECMF-150-S model claims to be “10-15% quieter”, yet that description says sound levels are 31-50 dB depending on fan speed. This math doesn’t add up at all. If the “silenced” model were truly 10% quieter than 31 dB it would only be 28 dB, not 31. And since the “silenced” model runs at 50 db at full speed, 15% quieter would be 42.5 db, not the 31 advertised here.
Bottom line: don’t expect this model to be the same noise level as their silenced model at half the price, it won’t be. Always treat the manufacturer’s product description with some skepticism.
This inline duct fan features a brushless EC Motor and dual jet type blades in a coated steel housing to deliver 288 CFM airflow rate using just 36 Watts at max speed. The variable speed controller decreases speeds without background noise or hum. It will also work with their wireless remote control (Model: ECMF-WR) and their thermostat speed controller (Model: SC-ECMF).
AC Infinity Cloudline Lite A6, Quiet 6” Inline Duct Fan ($89)
Cheapest quiet inline duct fan: 6″
The AC Infinity Cloudline Lite A6 is a cheaper version of the AC Infinity S6 inline duct fan model discussed above. It delivers a bit less airflow (352 CFM vs 402 CFM) with a bit more noise (34 dBA vs 32 dBA) than the S6. It’s slightly louder than the TerraBloom ECMF-150 6 inch fan, but it’s more powerful as well.
It includes a wired 10-speed fan controller and is compatible with all Cloudline Series smart controllers.
Mixed flow design combined with an EC-powered motor for a truly quiet and energy efficient performance.
If you’re looking for the quietest inline duct fan in the six inch size then this probably isn’t the unit you’d want. But if you want a lower-priced alternative that isn’t that much louder than their S6 model, then this A6 fan is a good option to consider.
8 inch size: quietest inline duct fans
The best way to get the quietest inline fan for grow tent or grow room setups is to run a larger duct fan at lower speeds, reducing motor noise and the sound of rushing air through smaller ducts. Using an 8 inch inline fan may be the best option for large grow tents and grow spaces, particularly those with long, curved duct runs which reduce efficiency. But in general an 8 inch fan is definitely overkill for small and midsize grow tents.
AC Infinity Cloudline S8 Inline Duct Fan ($169)
Best overall inline duct fan 8″ and best value
The 8″ AC Infinity Cloudline S8 fan is built to ventilate hydroponic grow rooms, transfer heating/cooling, circulate air, and exhaust odors. It delivers a powerful airflow of 807 CFM at only 39 dBA, making it one of the best silent grow tent fans you can buy.
It’s much more powerful than the 8 inch TerraBloom “silenced” inline fan (which has only 569 CFM of airflow at only 31-51 dBA). It also costs nearly half as much, so for growers on a budget the AC Infinity S8 is a much better value considering the difference in sound levels.
The AC Infinity features an 8-speed manual controller with a mixed flow design combined with an EC-powered motor for a truly quiet and energy efficient performance.
Another cool feature is that you can use a single controller with multiple AC infinity fans at different sizes. This is helpful if you want to use a larger fan for exhaust and a smaller size as an air intake fan.
All of the AC infinity inline duct fans tend to offer high performance at very quiet sound levels in their respective sizes, and this unit is no exception.
TerraBloom ECMF-200-S 8″ Silenced Inline Duct Fan ($299)
Runner up: Best silent inline fan 8″
TerraBloom’s 8″ ECMF-200-S silent inline duct fan was built to run quietly. It delivers 569 CFM of airflow at only 31-51 dBA (measured ducted, 6-ft from inlet). It costs more than other 8 inch fan models due to the sound-proof design.
These “silenced” fans have a 2″ thick layer of acoustic sound-insulation foam inside a steel body and four vibration-reducing suspension springs. This reduces sound by 10-15 dBa of noise output reduction depending on speed setting versus regular, non-insulated ECMF fans of matching size. Such noise output is perceived as 50% quieter to human hearing.
But it’s still not as quiet as the AC Infinity 8″ inline fan. At nearly 2x the cost.
This fan uses a brushless EC Motor and dual jet type blades to deliver a 569 CFM airflow rate using just 74 Watts at max speed. ECMF-200-S is HVI Certified and meets the ENERGY STAR Most Efficient 2021 Criteria. It lets you choose any speed from 0 to 100% using the included variable speed controller without creating background noise or hum at low speeds.
Like all of the TerraBloom inline fans this 8″ model allows you to to upgrade to a wireless remote control (Model: ECMF-WR). You can also further increase control of your tent environment with a thermostat speed controller with temperature programming (Model: SC-ECMF). This fan also supports pulse-width modulation (PWM) controllers and 0-10V controllers via a 3.5mm audio port.
This fan is ETL Listed, HVI Listed, Energy Star certified, and comes with a two year warranty.
TerraBloom ECMF-200 8″ Inline Duct Fan ($159)
TerraBloom ECMF-200 duct fan is the more basic version of the ECMF-200-S silent inline fan model described above.
Like the S model, this fan delivers 569 CFM airflow rate at 62 dBA using just 74 Watts at max speed. The built-in speed controller allows you to choose any speed from 0 to 100% without creating background noise or hum at low speeds. On the lowest setting the fan’s noise level is 38 dBA.
It lets you upgrade to a wireless remote control (Model: ECMF-WR) or intelligent thermostat speed controller with temperature programming (Model: SC-ECMF). This fan also supports pulse-width modulation (PWM) and 0-10V controllers via 3.5mm audio port.
This fan is built with a coated steel housing that resists rust and protects motor and blades from accidental damage and harsh elements in grow tent and grow room applications. It has IPX4 ingress protection rating, is ETL Listed, and comes with a two year warranty.
This ECMF-200 fan is much cheaper than TerraBloom’s “silenced” model, and it’s a solid fan if you don’t care as much about getting the lowest noise level possible in your inline fan.
But if you’re looking for the quietest 8 inch fan, you’re better off with the 8″ AC Infinity fan which sells for about the same price point and delivers over 200 CFM air movement.
10 inch inline fan quietest models
AC Infinity Cloudline S10 10 inch Duct Fan ($269)
The 10″ AC Infinity Cloudline S10 fan delivers very high air output at a low noise level. It has 1201 CFM of air movement at only 48 DBA, making it the best quiet 10″ inline fan
The price point for the AC Infinity Cloudline S10 is considerably lower than the TerraBloom 10″ silenced fan while delivering more power at lower sound levels. So it’s an all around great value if you’re looking for the quietest inline duct fan at this size.
The S10 fan has an 8-speed manual controller utilizing pulse-width modulation (PWM). They also make a similar T-Series model that includes built-in temperature and humidity controls.
This inline fan kit also includes corded sensor probe, AC power plug, two duct clamps, and required mounting hardware. It measures 11.3 x 15.1 x 12.2 inches.
TerraBloom 10″ Silenced ECMF-250-S Fan ($399)
The TerraBloom 10″ silent duct fan model ECMF-250-S delivers 946 CFM at 52 dBA (measured while ducted, 6 feet from the inlet). It uses 126 watts of power.
Like the other TerraBloom silent grow tent fans their 10″ model has a 2″ thick layer of acoustic sound-insulation foam inside a steel body and four vibration-reducing suspension springs inside.
It measures 33.8 x 13.9 inches. ECMF-250-S is HVI Certified, ETL Listed, and meets the ENERGY STAR Most Efficient 2021 Criteria. It comes with a two year warranty.
The built-in controller lets you choose any speed from 0 to 100% using the included variable speed controller without creating background hum at low speeds.
It also allows you to upgrade to a wireless remote control (Model: ECMF-WR) or intelligent thermostat speed controller with temperature programming (Model: SC-ECMF). This fan also supports pulse-width modulation (PWM) and 0-10V controllers via a 3.5mm audio port.
It’s a bit more expensive than the AC Infinity S10 10 inch fan, yet it’s less powerful and louder — so it’s not as good a value. If you’re on a budget and want to stick with the TerraBloom brand, check out their ECMF-250 model below which costs about half as much as the silent 10 inch fan “S” model.
TerraBloom ECMF-250 10 Inch Inline Duct Fan ($219)
The TerraBloom ECMF-250 10″ duct fan is used in indoor grow facilities and vertical farms, as well as for heating and cooling transfer or commercial drying and air filtration applications. It can create negative pressure environments, simulate wind, exhaust odors and smoke, or intake fresh air from outdoors.
This model delivers 946 CMF at 65 dBA. It is similar to the ECMF-250-S Model, but it’s a bit louder since it lacks the 2″ insulated housing used by the S model.
It uses a brushless EC Motor and dual jet type blade to deliver a 946 CFM airflow rate using just 126 Watts at max speed. It translates into only $380 annual cost of 24/7 operation at max speed using $0.29 average cost per KWH. Our fans don’t “purge” or waste electricity at lower speeds. ECMF-250 is HVI Certified and meets the ENERGY STAR Most Efficient 2021 Criteria.
This EC fan’s speed controller can be set to run from 0 to 100% using the included variable speed controller without humming at low speeds. Upgrade to a wireless remote control (Model: ECMF-WR), intelligent thermostat speed controller with temperature programming (Model: SC-ECMF). You can connect pulse-width modulation (PWM) controllers and 0-10V controllers via 3.5mm audio port.
This TerraBloom ECMF-250 is the best value in quiet 10″ duct fans. At 65 DBA it’s a bit louder than the AC infinity 10″ fan which is only 48 dBA. But it’s also cheaper. So if you need a fairly quiet fan and you don’t want to spend a ton then this is a good option.
Quietest 12 inch inline fan
AC Infinity Cloudline S12 12″ Inline Duct Fan
The AC Infinity Cloudline S12 fan is a quiet 12 inch inline duct fan that delivers 1604 CFM of airflow at only 62 dBA at full speed. Impressive considering that there are some 4″ fan models that sound noisier than that.
12 inch duct fans are meant to ventilate very large grow rooms. This fan has an 8-speed manual controller powering an efficient EC motor controlled using Pulse Width Modulation (PWM). Dual ball bearings allow you to set it up in any direction. It measures 14.9 x 17.7 x 14.1 inches.
Like all of the AC Infinity Cloudline series, the same controller can be used to power multiple fan sizes. So it is very easy to add an 8″ or 10″ intake fan to offset the negative pressure that a 12″ inline fan creates.
Also available is Cloudline T12 which also includes built-in temperature and humidity controls with a 12-foot probe.
Quiet duct booster fan options
If you don’t need a lot of airflow, a quiet duct booster fan may be your best bet. They’re more affordable than standard inline fans, and some models are whisper quiet. Keep in mind that not all duct booster fans share these quantities, we’ve used a few (including one from Home Depot that sounded ridiculously loud given the pitifully low airflow).
The AC Infinity 4 inch duct booster fan costs around $26. It has 105 CFM at 28 dB, which is the same noise level as their full-size silent inline duct fan model. So it’s not all that quiet in a direct comparison since that full size model pushes way more air.
But at less than 1/3 of the price it’s great if you are looking for a cheaper way to provide air intake in grow tent or grow room setups.
Duct booster fans are perfect for grow tent air intake, as well as for exhaust in small tents such as a 2×2, 3×3, or 2×4. If using for exhaust you’ll need to use a short, straight duct run to avoid reducing the CFM level too much. They may be a bit underpowered if you plan to use a carbon filter.
You can further quiet duct booster fans using a variable transformer speed controller or a cheap fan speed controller, but read product descriptions closely as not all models will work with fan controllers.
inline fan noise reduction
In addition to buying the quietest inline fan you can afford, there are several other things you can do to provide inline fan noise reduction in your grow tent or grow room. Proper sizing, speed controllers, inline fan silencer boxes, and duct insulation all can help you keep your grow room or tent silent.
Properly sizing your inline fan
Properly sizing your fan unit to the grow tent or grow room is a must. Running a larger fan at 40% is usually much quieter than using a smaller fan at 100%, both in terms of motor noise/vibration and the rushing sound of air flow inside the ducting.
Having short, straight runs of ducting allows you to reduce fan motor speed while maintaining the same level of ventilation. Long curved runs can greatly reduce efficiency. Straight runs also help reduce inline fan noise from air movement within the ducts, a big factor in inline fan noise reduction.
Silent inline fans are rated by CFM, or cubic feet per minute. Usually you want to exchange the tent air once per minute. Plus the length of your duct run and the amount of curves reduce fan efficiency.
To determine the necessary CFM needed in your inline fan, multiply the height, width, and length of your grow space. For example, a 4x4x7 grow tent would need 112 CFM. But you also need to for the efficiency reduction due to the duct run and carbon filter, equaling roughly 150 CFM. So a quiet 4″ inline fan rated for 200 CFM would work well if running at 75%. But a 6″ inline fan rated for 400 CFM could move the same air when running at 30%, making it a much more silent inline fan setup.
Using an inline fan speed controller
Most silent inline fans use a built in speed controller so you can fine-tune exhaust rates for your tent or room. If you are looking to make your existing inline duct fan quiet and it doesn’t have a built-in controller there are several types of fan speed controllers available.
Cheap inline fan speed controllers
Cheap inline fan speed controllers let you choose from a few preset settings. If you need to quiet inline duct fan noise, adding a speed controller is the first step. The cheapest fan controllers do have drawbacks though. They can cause motor hum at low speeds, and can shorten the lifespan of the fan motor. It’s best to buy a fan controller matched to the fan if possible to be safe. For more expensive fans, consider getting a higher quality controller or look for models that have one built-in. Check out Vivosun or Cdmall for cheap speed controllers.
Variac fan controllers
Variac variable transformers allow you to choose from unlimited voltage options to reduce fan speed and quiet motor hum and vent air movement noise from inline duct inline fans.
Variable transformers work differently than cheaper speed controllers, and provide more precise control over the amount of electricity used by your inline duct fan.
They also don’t hurt motor lifespan the way cheaper speed controllers can, so they’re a good option if you’re buying a more expensive duct fan.
Inline fan silencer
An inline fan silencer is a great solution for grow tent or grow room applications where you need to blast inline fans at higher speeds to maintain proper air movement. Even the quietest inline duct fan run at high speeds creates rushing sound in ducts that can often carry beyond the grow room all the way to the end of the exhaust run.
An inline duct fan silencer, also known as an inline fan duct muffler, can help reduce the noise from air that exhausts from the vent. The duct muffler attaches right to the ducting. They usually contain neoprene foam in an egg crate pattern that will reduce fan noise by up to 50%. By reducing the sound of air movement with a duct muffler you can quiet inline fan noise levels for a more stealthy grow.
Inline fan silencer box
Making an inline fan silencer box is a great solution for grow tent or grow room applications where you need to quiet inline fans that run at higher speeds to maintain proper air exchange. The resulting motor hum can be quite loud.
Inline fan silencer boxes are constructed around the inline fan to block the noise. Usually in these setups the fan will be located outside of a grow tent because of the extra space they’ll take up. You can make a DIY inline fan silencer box using two inch thick foam insulation panels meant for wall insulation. Cut out your silencer box panels big enough to surround your fan, and secure with Gorilla tape. Don’t make it airtight and leave space between the fan casing and the panels, you don’t want the fan to overheat in a small air-tight box.
You can also make a more secure silencer box using plywood, and then line with foam insulation panels. Much more durable. Screw the inline fan right into the wooden box frame, attach two eye hooks at the top ends of the box, and then hang using bungee cords to absorb vibration.
Even the quietest inline fan silencer box won’t solve all of your problems with fan noise, but they will let you make the quietest inline fan setup possible.
Insulating grow tent ducts
Sometimes you can take all the steps outlined above to reduce noise from grow tent fans and you still will run into sound issues. This occurs most often when you need to run your inline fan at high speed — the rushing air is usually louder than the fan motor itself.
Wrapping flexible aluminum ducts with an insulating material such as a thick blanket works to muffle the sound. Make sure to use a non-absorbent material inside your tent or the humidity will cause mold issues as the fabric absorbs it. Secure with duct tape.
You can also buy insulation sheets meant to wrap duct runs outside of your tent. Make sure to only use ones made of cotton. Avoid fiberglass insulation around grow tents or exposed in grow rooms. You definitely don’t want fiberglass fibers to make their way into your tent and stick to your plants.
Summary: Quietest inline fan for grow tents and grow rooms
Inline fans from AC Infinity are the best bet if you are looking to buy the quietest inline fan for grow tent or grow room setups. They make quiet inline duct fan comes in all sizes: 4″, 6″, 8″, 10″, and 12″. They’re much quieter than other inline fans we’ve used.
4 inch inline fan quiet models are best for 2×2, 3×3, 2×4, or 4×4 grow tents. 6 inch inline fan quiet models are best for 4×4, 5×5, or similar sized tents, and they’re good for air-cooled light fixtures. 8 inch, 10 inch, and 12 inch inline fans are for larger grow rooms.
A silent inline duct fan isn’t the only way to provide inline fan noise reduction. Create short, straight ducting runs and use duct mufflers, an inline fan silencer box, and duct insulation to further muffle noises. And remember that the quietest inline fan for grow tent and grow room setups is a larger sized model run at lower speeds using a fan controller.