One of the most challenging parts of growing marijuana indoors is controlling the various smells coming from your grow room. Odor control can be crucial for indoor growers as it helps keep prying noses away and maintain the privacy of your space.

A carbon filter is a highly effective method that can eliminate over 90% of smells from an indoor grow space. When choosing a carbon filter, you need to choose one that fits your fan properly and it is big enough to circulate the air for your room.

Choosing the best carbon filter for grow room is way easier when you know what you’re looking for, and can effectively compare popular models. We’ve narrowed down your search to five carbon filters that are hugely popular among indoor cannabis growers.

Top 5 Carbon Filters for Grow Room

Last Updated: March 26, 2020

PRODUCT SIZE (INCH) CFM PRICE
Hon & Guan 6 No Info
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TopoGrow 6 450
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iPower 4 200
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TerraBloom 6 550
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Vivosun 4 350
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#1 Hon & Guan 6-Inch Carbon Filter

Coming first in our list is the Hon & Guan carbon filter. It comes highly recommended by a lot of indoor growers because of its durable design and high-quality filter. The main structure is made of galvanized steel, which is more durable compared to aluminum filters.

The base and filter flange of the main structure are interchangeable. The outer and inner mesh have sufficient open area for superior airflow. This unit features reversible smell filtration which can actually move the air in your room. You can use it as an exhaust or intake filter. You can use it to filter, purify, or move air.

The device is engineered for enclosed grow rooms. It will soak up and get rid of unwanted smells and promote better plant health by ensuring that the air is always clean. There are two ways you can install this filter. You can install it as an intake filter by placing the pre-filter outside or you can install it as an exhaust filter by placing the pre-filter inside.

Pros

  • Switchable base and reversible flange for longer use
  • Can be used as an exhaust or intake filter
  • Inner and outer mesh offers a more open area for superior airflow
  • Zinc treatment is resistant to chemical corrosion
  • Galvanized steel air odor control scrubber is highly durable

Cons

  • CFM rating is not provided
  • Could have better connection pieces

#2 TopoGrow 6-Inch High CFM Carbon Filter

The TopoGrow Carbon Filter comes with a quality design made absorbent carbon charcoal. This unit features a zinc anodized steel casing that is more durable than other materials. The casing makes it highly resistant to chemical corrosion.

Whether you need exhaust or intake air cleansing, the TopoGrow will meet those needs. This unit has a maximum scrubbing of 450 CFM, with an iodine adsorption rating of 950, which is highly efficient.

It has a carbon layer thickness of 1.5 inches with an operating environment temperature of -20 to 65 degrees Celsius. Its maximum endurable temperature is 400 degrees Celsius. This unit has a reversible filter base and flange, which extend the filter’s life. Not to mention the exceptional removal of pungent odors and smells for better privacy.

Pros

  • Superior air flow scrubbing of 450 CFM
  • Zinc anodized steel casing is highly durable
  • Changeable Velcro pre-filter helps to remove impurities
  • Reversible filter base and flange improves the filter’s life
  • Outstanding pungent odor control for superior privacy

Cons

  • Pre-filter may fail to perform admirably

#3 iPower 4-Inch Air Carbon Filter

The iPower 4-Inch Carbon Filter is a professional-grade filter with a cap that is engineered from high-quality aluminum material. It has superior lasting effects and maximum strength.

What’s most impressive is the iPower four-layer construction that starts with the inner mesh, virgin charcoal bed, outer mesh, and pre-filter on the outside. The inner, as well as outer mesh, provide a larger open area for increased airflow. The pre-filter; however, needs to be replaced every six months.

This unit features special virgin carbons obtained from the Earth’s pressurized sources. These carbons have a superior odor removal performance. The iPower has a reversible base and flange. You can easily flip the entire filter upside down to remount the base and the flange for the second year of scrubbing.

Pros

  • The high-quality aluminum cap has superior lasting effects
  • Four-layered construction guarantees effective performance
  • Increased airflow, thanks to the inner and outer mesh design
  • Virgin carbon is very effective at removing pungent odors
  • Reversible base and flange increases usability

Cons

  • Pre-filter has a shorter lifespan

#4 TerraBloom Activated Charcoal Filter

It may be fourth on our list, but the TerraBloom is built to perform. It is made of high-quality RC-48 charcoal carbon obtained from Western Australia.

The carbon bed incorporated in this unit is machine packed and 46 mm thick. Not to mention that it is integrated with very small granules for better filtration.

You will like the aluminum construction that is very lightweight. The aluminum flange and base come pre-installed.

TerraBloom is probably the only brand that will provide you with two machine washable pre-filters. They are available in black as well as white colors.

The filter has an airflow rating of 550 CFM, which can be used for up to twenty-four months. It is capable of filtering plant-based allergens along with other foul smells.

Pros

  • Lightweight and easy to install aluminum construction
  • Built with high-quality activated virgin carbon
  • Thicker carbon bed for superior smell control
  • Two machine washable pre-filters for effective air cleaning
  • Very effective at removing plant-based allergens

Cons

  • May require ducting to attach to a fan

#5 Vivosun 4-Inch Air Carbon Filter

Coming last in our list is the Vivosun Carbon Filter. This one also features virgin Australian charcoal that delivers reliable airflow filtration.

It is incorporated with RC 48 (1050+) carbon that is very much capable of capturing more air contaminants than conventional filters.

Unlike traditional carbon filters, the Vivosun comes with a reversible base and flange. This simply means you can flip the bottom and the flange to extend the filter’s life by a year or so.

The four-layered construction includes an outer and inner mesh. The mesh provides a larger open area for superior airflow. The design is also incorporated with a Velcro pre-filter.

You can use the Vivosun as a carbon filter fan combo. It has an exhaust or intake filter in different configurations, such as with ventilation ducts, air exchange fans, and six-inch inline fan.

Pros

  • Outer and inner mesh allows for effective airflow
  • Reversible base and flange provides longer life
  • Can be used as an exhaust or intake filter
  • Carbon particles used to eliminate more air contaminants

Cons

  • May not be suitable for a larger grow room
  • Pre-filter has a shorter life

What to Look For In a Carbon Filter

Grow Room Size

What size carbon filter do you need for your grow room? This is the very first question that you have to ask yourself.

Start by calculating the volume of air used in your grow room. For example, if your grow room is 10 by 12 feet, and your ceiling is 8.5 feet high. The volume is 1020 cubic feet.

That’s about 29 cubic meters for any sensible metric people out there. We are talking about the volume of air used for actual growing.

If you have a room this size, but you are only using half of it to grow your plants, you could divide the volume in two.

Similarly, if you are growing in a tent, it is the air volume of the grow tent itself that you need to take into as far as your calculations go.

Fan Size

Then go ahead and calculate the size of the extraction fan you need. You can use a fan speed controller to give yourself some wiggle room.

An indoor grow room full of mature plants would most certainly have a high demand for Co2 and transpires more moisture into the air.

This is when you actually need to exchange your grow room air once every sixty seconds. Young plants don’t need so much air exchange.

In our example, we need to exchange 1020 cubic feet of air each minute. Therefore, you would need a powerful exhaust fan, such as a 10-inch hyper fan that can shift 1065 CFM.

Air Flow Requirements

How do you know how much CFM you need? First, you have to understand what CFM is to be able to answer this question.

Well, CFM refers to cubic feet of air per minute. To compute the ideal CFM that your carbon air filter must have, you need to multiply the height, length, and width of your grow space.

You can use this number to shop for a suitably rated intake fan. For instance, a CFM of about a third of the grow space volume.

A carbon filter’s resistance would require you to increase the computed volume by twenty percent since the fan needs to be slightly stronger to overcome the resistance.

The simplest way to determine the ideal CFM is by using a CFM calculator. The dimensions of your grow room are very crucial when determining airflow requirements.

If we use a CFM calculator, our room size example would require a carbon filter with a CFM of 490, if you will be using a single grow light.

What is contained in the Carbon Filter?

Activated carbon refers to charcoal that has been exposed to high temperatures and steam in the absence of oxygen.

Activated carbon has a microporous structure that provides a very large surface area to weight ratio that facilitates surface adsorption.

The performance of a carbon filter is determined by the quality as well as the amount of carbon that is present, by the activation process, by the airflow pattern, and by the moisture in the air.

A given amount of carbon can only be so absorbent of a specific amount of compounds. Therefore, the more carbon present, the heavier or denser the filter would be and the longer it will work.

All absorption ratings are based on a per gram unit of carbon. More weight equals more absorptive capacity.

The adsorption capacity and the rate of the removal varies greatly with the carbon used. The activated charcoal efficiency is a function of various parameters.

The parameters include the degree of activation, nature, source, particle sizing, and volume of charcoal used.

Pre-Filter Included

The life of a carbon filter can be extended by using a less expensive pre-filter to remove some of the impurities from the grow room.

Most top-rated carbon filters for grow room come with a pre-filter to remove sediments.

Those with a pre-filter in a separate canister are superior to those with carbon and pre-filter sharing a container because they are easier as well as cheaper to maintain.

Such sediment filters will pick up many of the larger contaminants that would otherwise pass right through the carbon, making this combination a very good idea.

High-Performance Fan

The other important consideration you will have to make is choosing which high-performance fan your carbon filter uses.

The most popular size for most grows room sizes is a 10-inch hyper fan. This type of fan is compact with more CFM per watt than conventional fans.

You should look for a fan with a superior CFM than your carbon filter in order to overcome the resistance that is normally associated with carbon filters.

The ideal fan should have a rating of at least 1065 CFM. This rating is ideal for small (324 cubic feet) or large (1020 cubic feet) rooms of different sizes and so on.

Final thoughts

Grow rooms and grow tents are a perfect solution for indoor growing, but they need to be ventilated correctly. The most important thing to consider when choosing a carbon filter is that it needs to extract the hot air away, not just out of the tent itself, but out of the room.

By choosing a high-quality carbon filter, you can make sure that your grow area is well ventilated, your plants are getting the air they need, and you’re keeping unwanted odors at bay.

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