Best 4 inch carbon filter for grow rooms (Updated 2018)

Table of Contents

by | Oct 16, 2015

Although there has been a lot of progress in various national laws around the world those past few years, our plants are still considered illegal in many places, exposing us to potential legal problems.

As much as we all love the sweet smell of our crops and enjoy noticing its impressive increase during the final stages of our culture, it can become a serious issue for most of us.

Make Sure Air is Circulating Through Your Garden

Inline fans are essential for growing cannabis in a tent or grow room. Growing indoors with the right equipment allows you to have more growing seasons per year.

That’s why carbon filters for grow rooms are so handy! The activated carbon they contain will absorb anything from the exhausted air, helping you gain grow room odor control and keeping you safe from nosy neighbors and law enforcement agents.

On top of that, a grow tent with the best carbon filter eliminates any airborne pathogens potentially harmful to your plants.

Best Carbon Filter Comparison Table


iPower 4 Inch Air Carbon Filter Odor Control Scrubber for Duct Inline Fan, Reversible Flange, Prefilter Included

- Air Flow: 200CFM; Dimensions: 4" Flange Ducting x 12" Length
- Extended Service Life
- Pre-Filter included
- Effective Odor Control


Phresh 701005 Carbon Air Filter, 6 by 16-Inch, 400 CFM

- Flange & pre-filter included
- Unique "Anti Air Bypass" System


Phresh Duct Silencer 4 in x 12 in

- Sound reducing acoustic foam decreases fan noise by up to 50%
- Use with fans in conjunction with carbon filters, light systems and more
- Durable and light weight aluminum body; Compact size is easy to install


Phresh Filter 4 in x 12 in 200 CFM

- 46mm (18") RC-48 activated, certified virgin carbon bed
- Flange & pre-filter included
- Unique "Anti Air Bypass" System


VenTech VT IF4+CF4 IF4CF412 Inline Duct Fan with Virgin Charcoal Carbon Filter Combo

- superior air flow and be suitable for various environments
- made of steel construction with powder coated baked paint


VIVOSUN 4 Inch Air Carbon Filter Odor Control with Australia Virgin Charcoal for Inline Fan

- Pre-filter Included
- Effective Odor Control
- Two Reversible Ways: Used as intake filter and exhaust filter


iPower 4 Inch Air Carbon Filter Odor Control Scrubber for Duct Inline Fan, Reversible Flange, Prefilter Included

Phresh 701005 Carbon Air Filter, 6 by 16-Inch, 400 CFM

Phresh Duct Silencer 4 in x 12 in

Phresh Filter 4 in x 12 in 200 CFM

Most new growers underestimate the smell’s power and will rush to buy filters in a hurry when confronted with its pervasive presence. In order to avoid this situation and before choosing the top carbon filter you should consider:

  • Your fan’s CFM (Cubic Feet per Minute), it’s the most frequent rating you’ll find on your fan and represents the air volume it can suck out during a minute. Your filter rating must always exceed it (ideally by 20 to 30%) to ensure a good exhaustion.
  • Vacuuming the filter before first use to remove carbon particles, as they can be very hard to remove. You can even do it outside for more security.
  • Being careful if using a cheap inline fan and carbon filter. Inline fans like the one in your bathroom are often not powerful enough for carbon filters, resulting in a short lifespan.

So remember a good filter is useless without a proper exhaustion.

filter and fan grow tent setup

Photo source:

Top Incline Fans for Your Grow Room – Carbon filters review

Grow rooms are great spaces, but they can be very noisy! The fans, exhausts and other items used in the grow room produce sounds that can drive a sane person crazy very quickly. Luckily, silencers and filters that keep the noises down are available for purchase and the best of them are found below. Choosing one of these products enhances your grow space and keeps things quiet and smooth.

Best 4 inch carbon filter

1. iPower 4 Inch Air Carbon Filter Odor Control Scrubber

Buy iPower 4 Inch Air Carbon Filter Odor Control Scrubber for Duct Inline Fan, Reversible Flange, Prefilter Included

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  • 1050+ IAV Australia charcoal
  • Reversible flange
  • Pre-filter included
  • Odor control for better privacy
  • Cleaner air to promote better health

The iPower 4-inch air carbon filter has a 200 CFM airflow rate and measures 12-inches in length. The heavy-duty product has a 1050+ IAV Australia Virgin Charcoal base that extends the product lifetime. This base provides a filter that can work around the clock for up to 2-years of time. It is one of the longest operating, budget-friendly filters sold today. There is an included pre-filter that increases the product versatility. Use it as an intake or an exhaust filter for added versatility. The lightweight design is an attractive feature of this filter. In fact, it is 50% lighter than the leading filters on the market today, weighing only about 6-pounds.


Doing Things Differently


Odor control is easy for this filter. If you’re concerned about neighbors smelling your plants (or even visitors that come to your home,) this filter offers effective odor control that keeps the smells at bay so you’re the only person who knows what is inside. Furthermore, the filter keeps unpleasant odors that can occur in a grow room at bay. The aluminum-designed base is strong and durable, maximizing the lifetime you’ll get when using this unit.


Who Should use This FIlter?


For growers searching for a customer-recommended product, this one makes the cut. The unit sells for a super low price and is an amazing budget-friendly filter that works for any need. Amazon users enjoy this product and its many features and above-average performance. They enjoy it so much they rate it with a 4.2-star rating out of a potential 5-star rating.



  • 1-year warranty
  • Trusted brand
  • Reversible flange
  • Includes pre-filter
  • Cleans and purifies the air
  • 53% open area air flow
  • Can be used in grow rooms, grow tents, and with other systems



  • Small pinholes can be difficult to use
  • Does Not block odors as well as some of the other units

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This is our top pick! We highly recommended it as it offers the best balance between price and efficiency. Its Australian virgin charcoal will provide an odorless air exhaustion for several sessions.

It features a pre-filter to prevent excessive dust from clogging the inside and detailed instructions to open the can and reverse the filter, increasing its lifespan.

2. Phresh 701003 Carbon Air Filter, 4 by 12-Inch, 200 CFM

Buy Phresh Filter 4 in x 12 in 200 CFM via Amazon

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  • 46mm (18″) RC-48 activated, certified virgin carbon bed
  • Flange & pre-filter included
  • Unique “Anti Air Bypass” System
  • Sealed, bagged, boxed and labeled directly after manufacture for optimum life span
  • handling and presentation
  • Large selection of sizes available to fit any application

Phresh is a trusted name in the grow industry. They’re known for creating high-quality, professional grade, extremely durable products that enhance your grow. This filter is one of the company’s best products and certainly lives up to the expectations that people have of the Phresh products. This high-quality 4-inch filter has a 46mm RC-48 activated certified virgin carbon bed for added durability and with the flange and pre-filter included, it is easy to use this product from the very start of your grow until the finish.


Why use the Phresh Filter?


The filter uses a unique anti-air bypass system that prevents more dust, allergens, and mold from entering the room. The filter keeps the air cool, comfortable, and crisp, ensuring that your plants have an environment in which to thrive. And, it has a unique cone-shaped base that helps increase the smooth airflow enjoyed in the grow room.


An Inside Look


The filter uses nano carbon felt technology to product quality air flow throughout the room. It is easy to detect the changes in the air once this filter is put to use. It is confident to say that your cannabis plants will thank you for this addition! Easy-to-install and easy-to-use, the affordably-priced product can keep the air in a room of about 400-square foot clean and fresh.

The name says it all and when you want a room that is healthy and fresh, this product can certainly accommodate your needs. The product is competitively priced and while there are cheaper models, they fail to offer the same impeccable features this filter offers. Amazon customers seem to agree and have given this filter a 4-star rating out of a potential 5-star rating.



  • Lightweight at just 4-pounds
  • Anti-air bypass system
  • Easy-to-use
  • 51% custom mesh open-air rate




  • Flange is non-removable
  • Costlier than some of the other filters

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This Phresh carbon filter is a high-end product. With a reported service life exceeding two years, it’s among the most performant models on the market. Slightly longer than the previous one, it is sturdy built with good quality materials and thus relatively light-weighted.

It’s a really good item but its cost is higher. We recommend it for those with a bigger budget!

3. Phresh Duct Silencer 4 in x 12 in

Buy Phresh 701200 Duct Silencer, 4-Inch by 12-Inch via Amazon

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  • Sound reducing acoustic foam decreases fan noise by up to 50%
  • Use with fans in conjunction with carbon filters, light systems and more
  • Attach a Phresh Silencer to the intake or exhaust side of a fan; Use on both sides for maximum sound reduction
  • Durable and light weight aluminum body; Compact size is easy to install

Rated as one of the best products of its kind sold today, the Phresh Duct Silencer fits a 4 x 12 duct system. Don’t depend on the word of others to decide if it is a top product, however, and learn this information firsthand. The affordable price ensures that it isn’t a big loss if the silencer fails to meet your expectations, though that is a rare occurence.


How to use The Duct silencer


To use this duct silencer, simply add it to your grow room on a fan, carbon filter, or other accessories that might bring noises. Instantly, the silencer quietens the room and reduces the noises the fan produces. This silencer ensures that you get a thorough operation that is quite throughout the day.


Benefits of the Silencer


The price is a great benefit of this silencer. even people on a budget find the price to be beneficial to their needs. Aside from the low cost, the fact that it reduces noises by up to 50% is something that users will appreciate. It works well with many different systems and has an excellent user rating.


More to Love


This silencer has a one-year warranty accompanying it, so users get the satisfaction of a working product for this time period. It is built of high-quality aluminum material and is easy-to-install.

Using the Exhaust Fan


You can install the silencer on the inside or the outside of the exhaust fan. Many users purchase two silencers and use one on each side for more effective noise control. Whether you choose one silencer or two for maximum noise reduction, you’ll be pleased with the results and the silence that soon will fill the room.



  • Reduces noise levels of the fan by up to 50%
  • Affordable
  • Includes a warranty
  • Works well with most other systems



  • None to note

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4. Phresh 701005 Carbon Air Filter

Buy Phresh 701005 Carbon Air Filter, 6 by 16-Inch, 400 CFM via Amazon

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What we love:

  • It’s long lasting – up to 2 years
  • It is available in many sizes
  • It’s very light
  • It’s easy to install

What needs improvement:

  • Price

The Phresh carbon air filter, model 701005, is a six-inch carbon air filter that creates quality airflow in your grow room. It is 16-inches long, easy-to-install, and recommended by users for its high-quality functions. The filter has an RC-48 activated certified virgin carbon bed and includes both a flange and a pre-filter. The flange is riveted, however, so it cannot be removed. Unlike many other filters, this product has an anti-air bypass for improved air quality.


A Durable Product


The solid product construction is perfect for a grow room. It helps keep the air fresh, prevents bug intrusions, and ensures that pollen, dust, and dirt are never a concern. The filter maintains a 90% airflow at all times, which is considerably better than the competitor products. It is constructed from 90% recycled materials and has a lifespan of up to 2-years. The small size makes the filter easy to install in most any area, regardless of its size. And, it is always easy-to-use, even for first-time users.


Why use this Filter?


Amazon users like this product and cite only a few disadvantages. Users have given the product a 4-star rating and really enjoy the sleek, yet rugged style of the filter. This is out of a possible 5-star rating. The biggest disadvantages are the reduced expenses since it is priced nearly double the price of some of the air filters out there. The well-known brand is trusted, however, and most consider it a splurge filter worth the few extra dollars. Using this filter inside of your grow room makes it very much a real possibility that you’ll grow the perfect cannabis plant (and what a filter and fan to use in other areas of the home, too.)



  • Includes batteries
  • Easy-to-install
  • Air bypass system
  • Long lifetime
  • Initiates the latest technology



  • More expensive than other products on the market

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5. Vivosun 4-Inch Air Carbon Filter


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It features superb odor control so no smells escape the grow room, enhancing privacy where it is needed the most. The 4-inch filter is made of high-quality, durable materials for a long-lasting lifetime. The carbon filter works well in most any environment indoors and always provides superior airflow that keeps the grow room perfect for a thriving cannabis plant. There is an outer mesh and an inner mesh that improves the airflow quality from the filter.


Why Choose Vivosum Air Carbon FIlter?


It is a versatile product that works as an intake filter or reverses it to use as an exhaust filter. There is a switchable flip to control the product usage. It also includes a pre-intake filter with velcro that is super simple to change. The filter is easy to attach to your fan and includes 050+ RC 48. There are four mounting options to choose from. All of the supplies needed to mount must be purchased separately.


A Filter Users Love


Amazon customers give the filter a 4.6-star rating out of a possible 5-star rating. It doesn’t get a lot better than this amazing rating. It is customer-recommended and has surpassed expectations of hundreds of customers. Although there are a few disadvantages, the product feature and ease-of-use make up for them and make this a product worth the low price.  It can likely benefit you as much as it has many other growers before you.


In the Box

  1. 4-inch charcoal carbon filter
  2. Pre-filter
  3. Carbon Filter Belts



  • Amazon Choice product
  • Lightweight, compact size
  • 1-year warranty
  • Excellent customer service
  • 53% open area for increased airflow
  • Great price
  • Customer-recommended product
  • Works in most grow rooms



  • Provides less-efficient air-quality than some of the more expensive filters
  • Doesn’t include mounting supplies

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6. VenTech VT IF4CF412 Inline Duct Fan with Virgin Charcoal Carbon Filter Combo

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The VenTech VT IF4CF412 Inline Duct Fan has a charcoal carbon filter included so it solves two needs in one. The four-inch fan has a 7.50” CFM dimension, a power level of 65, AC voltage of 110v, and a 4-inch duct carbon. Everything needed to provide cool, crisp air inside your grow room is contained within this box so you’re ready to start as soon as it is purchased.

Price & Features

This fan offers a good value for the money. The warranty ensures that it provides you with 365-days of use, all for a super-low price. It is one of the better-priced units and since it offers the filters, fan, and mounts, it is easy to assemble without any unnecessary trips to the hardware store to pick up parts. Plus, you save the trouble and headache of making a separate fan purchase.

People Love The VenTech Inline Duct Fan

This fan has earned a 3.5-star rating on Amazon, with the biggest customer complaint being its longevity. Nonetheless, most users say that it is worthwhile, serves their needs wonderfully, and that it is a purchase worth making. Furthermore, it is a versatile fan that can provide refreshing air anywhere in the house, so if you change grow room locations, there is no worry if the fan can move with you. And, it is suitable for grow rooms of all sizes so that is yet another concern that’s gone.

In the Box:

1- 4” Fan
1- 4” Filter
1- Fan Mount
2- Instruction Booklets


  • Energy-efficient
  • Good for consistent use
  • Aerodynamic, durable steel construction
  • 1- year warranty
  • Easy-to-use
  • Everything needed to install included in the kit


  • Louder than other fans
  • Some users say that the fan has a bad smell when it is in use
  • Frequent repairs/parts replacements may become necessary


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– Read full review of this filters here – Phresh 701005 Carbon Air Filter

Phresh Filters are the lightest available. It is all thanks to aluminum top and bottom. Aluminum is light, so it significantly allows to reduce the weight of the whole product. The company also came up with a way to place inside the RC-48 Australian activated carbon that makes the filter more efficient and light. This special carbon is very absorbent thanks to its porous surface. Manufacturer, for best results, also used the purest form of charcoal called “activated virgin” carbon. Such construction allows the filter to absorb up to 108,3% of its own weight. On top of that, the unit keeps 99,9% of bugs, moulds, pollen and dust away

Although Phresh 70100 and other filters of this company are one of the more expensive, they do have a long lifespan. When used according to manufacturer guidance the product can last up to 2 years. Such long span is partially due to high-quality pre-filter fitted within the unit.

Worth the investment, this duct silencer will match any 4’’ ducting, reducing noise nuisance a fair bit. It’s very light and comes highly recommended for those of you with smaller structure grow tents who wish to have a noiseless environment.

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