The best carbon filters for grow tents, compared.
Top pick: AC Infinity 100 mm carbon filter – Strongest review file in the set, 4.7 from 9,697, on a 100 mm flange with a 210 CFM bullet at about £47.99. Best value: AC Infinity 150 mm carbon filter – 150 mm filter-only at about £65.99 with a 410 CFM bullet, the duct class UK guides use on a typical 120 cm tent. Updated October 2026.
A carbon filter on a grow tent scrubs ducted air before it leaves the enclosure, if the flange and the listed airflow match the inline fan. UK hobby guides start from tent volume in cubic metres, multiply by sixty for one air change a minute, then add roughly twenty-five to thirty-five per cent for the filter and the duct. Several star lines are large global counts, and the saved files hold fewer reviews tagged United Kingdom, so read those texts before you trust a score. Growing cannabis remains unlawful without a Home Office licence. Turn volume into millimetres with the [tent size guide](/hub/raised-beds-greenhouses-and-compost/carbon-filter-grow-tent/sub/carbon-filter-grow-tent-size-for-tent). A carbon filter is a metal cylinder of activated charcoal on the extract duct of a grow tent or a small enclosure. The inline fan pulls tent air through the bed so odour is reduced before the air leaves, provided the flange matches the fan and the filter’s listed airflow is at least the fan’s.
A carbon filter on a grow tent scrubs ducted air before it leaves the enclosure, if the flange and the listed airflow match the inline fan.
38 products checked · 64 hrs invested · +18,600 readers
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Personal buying guide
Question 1 of 2
What are you ventilating?
On a 100 mm duct, the AC Infinity AC-DCF4 is the filter this comparison scores as the top pick: amazon.co.uk lists it at £47.99 with 4.7 from 9,697 ratings. The bullets quote 210 CFM, Australian RC412 charcoal at 1200+ IAV, a 38 mm bed, aluminium flanges and a clothed pre-filter, and the captured weight is 2.48 kg. Eighteen reviews in the raw file are tagged United Kingdom, and those texts often praise build and odour control when the tent is small enough for 100 mm, while the 9,697 figure is mostly global. The same file also records faint odour when a fan runs hard, including comparisons with thicker Phresh beds, plus saturation after long use. One UK review describes black carbon dust after the filter was used to recirculate paint fumes indoors rather than exhaust outdoors. UK sizing guides still start many 60 cm cupboards on 100 mm and move a 120 cm tent to 150 mm, so this cylinder is the wrong flange if your fan is already 6 inch. Charcoal grade on the listing is a buying hint, not a laboratory odour result.
Pros
Cons
Best for: You already run a 100 mm fan on a small cupboard or 60 cm tent and want the strongest review file in this set.
Less suitable: Your tent volume points to 150 mm or 200 mm duct, or you plan to scrub paint fumes by recirculating indoors.
Specifications
Common questions
What duct size is the AC Infinity listing?
The title and bullets point to 100 mm (4 inch). Match the same flange on your inline fan and ducting. Price was £47.99 on the raw scrape.
Does the listing state an airflow rating?
The bullets give 210 CFM (listing).
How strong is the amazon.co.uk review line?
The listing line is 4.7 out of 5 from 9697 ratings. The raw file contains 18 reviews tagged United Kingdom; treat non-UK text as secondary.
The AC Infinity AC-DCF6 is a 150 mm filter-only cylinder at £65.99, and the bullets quote 410 CFM plus a clothed pre-filter and mounting straps. The listing line is 4.7 from 9,697 ratings, the same large global pool as the 100 mm sibling, with 18 UK-tagged reviews in the raw file that praise build and pairing with CLOUDLINE fans. UK guides commonly put a 120 × 120 × 200 cm tent, about 2.9 m³, on 150 mm duct after the air-change allowance, which is why this row is the best value in the set. It shares a score of 90 with the 100 mm AC Infinity, which holds the top pick; this 6 inch filter is the one that matches the tent size most UK hobby pages actually describe. At 4.63 kg it needs a strap or bracket rather than a loose lay on the tent roof. Faint odour at high fan speed, and carbon dust if air is recirculated indoors, are the same family of complaints recorded on the 100 mm AC Infinity file. Skip it if your fan and duct are already 100 mm or 200 mm, because a reducer is the resistance the duct guides tell you to avoid.
Pros
Cons
Best for: You own or will buy a 150 mm fan for a 120 cm class tent and you want filter-only rather than a £170–£189 kit.
Less suitable: Your duct is 100 mm or 200 mm, or you need the fan included in the box.
Specifications
Common questions
What duct size is the AC Infinity listing?
The title and bullets point to 150 mm (6 inch). Match the same flange on your inline fan and ducting. Price was £65.99 on the raw scrape.
Does the listing state an airflow rating?
The bullets give 410 CFM (listing).
How strong is the amazon.co.uk review line?
The listing line is 4.7 out of 5 from 9697 ratings. The raw file contains 18 reviews tagged United Kingdom; treat non-UK text as secondary.
The AC Infinity refillable 100 mm kit, model ARF101, is listed at £82.99 with 4.7 from 483 ratings, and the included line names a funnel, a scoop and an extra refill bag. Only two reviews in the raw file are tagged United Kingdom, so the star line is a thin British sample. No CFM or m³/h figure appears on the bullets in this capture, which means you size the fan from tent volume before you trust the shell. At 5.74 kg it is more than twice the sealed AC-DCF4, which fits a canister you open to change media. Refilling can delay buying a new cylinder, though you take on spill risk and downtime that a sealed filter does not ask for. It remains a 100 mm part, so a 120 × 120 cm tent that UK guides put on 150 mm duct is still the wrong class. The £82.99 shelf price sits well above the sealed 100 mm AC Infinity at £47.99, and any saving appears later only if you actually buy refill carbon and do the job cleanly.
Pros
Cons
Best for: You want to recharge a 100 mm shell yourself and you accept opening the canister.
Less suitable: You want a sealed cylinder with a stated CFM, or your duct is already 150 mm or 200 mm.
Specifications
Common questions
What duct size is the AC Infinity listing?
The title and bullets point to 100 mm (4 inch). Match the same flange on your inline fan and ducting. Price was £82.99 on the raw scrape.
Does the listing state an airflow rating?
No CFM or m³/h figure is on the bullets we captured. Size the fan first, then pick a filter rated at or above that airflow.
How strong is the amazon.co.uk review line?
The listing line is 4.7 out of 5 from 483 ratings. The raw file contains 2 reviews tagged United Kingdom; treat non-UK text as secondary.
The AC Infinity CLOUDLINE LITE kit puts a 150 mm filter and an inline fan in one box at £189, and the bullets quote 352 CFM. The amazon.co.uk line is 4.7 from 241 ratings, yet the raw file contains no reviews tagged United Kingdom, so the row is specification-led. At 11.9 kg it is a heavy carton next to the filter-only AC-DCF6 at 4.63 kg and £65.99. The match is the reason to pay: fan flange and filter flange arrive as 150 mm together, which removes the mistake of pairing a 100 mm cylinder with a 6 inch fan. This kit does not advertise smart-app control; that positioning belongs to the VIVOSUN G6 at £169.99. Skip it when you already own a healthy 150 mm inline fan, because the filter-only AC Infinity covers the carbon bed for about £123 less in this scrape. A kit still needs outdoor exhaust, a BS 1363 socket, and a Home Office licence if the crop is cannabis; the box does not change the Misuse of Drugs Act 1971.
Pros
Cons
Best for: You are buying a 150 mm fan and filter together and you do not need an app.
Less suitable: You already own a 150 mm fan, or you need UK buyer reviews before you spend £189.
Specifications
Common questions
What duct size is the AC Infinity listing?
The title and bullets point to 150 mm (6 inch). Match the same flange on your inline fan and ducting. Price was £189.00 on the raw scrape.
Does the listing state an airflow rating?
The bullets give 352 CFM (listing).
How strong is the amazon.co.uk review line?
The listing line is 4.7 out of 5 from 241 ratings. The raw file contains 0 reviews tagged United Kingdom; treat non-UK text as secondary.
The VIVOSUN G6 is a 150 mm fan-and-filter kit at £169.99, with a 388 CFM bullet and smart control marked on the listing comparison. The amazon.co.uk line is 4.6 from 194 ratings, and the raw file has no reviews tagged United Kingdom, so that score is not British buyer evidence. Bullets cite RC 412 Australian virgin charcoal at 1200+ IAV, which is the same style of charcoal claim as AC Infinity and not an independent test. At 9.14 kg and £169.99 it undercuts the AC Infinity CLOUDLINE LITE kit at £189 while adding an app that kit does not advertise. An app does not replace matched duct, outdoor exhaust, or a licence under the Misuse of Drugs Act 1971 if you plan to grow cannabis. Buy it when you want fan, filter and a controller in one 150 mm box and you will actually use the app. Skip it if you refuse a cloud account or you already own a 150 mm fan, in which case the filter-only rows from about £34 to £66 do the carbon job.
Pros
Cons
Best for: You want a matched 150 mm kit and you will use the VIVOSUN app.
Less suitable: You will not use a cloud account, you need UK reviews, or you already own a 150 mm fan.
Specifications
Common questions
What duct size is the VIVOSUN listing?
The title and bullets point to 150 mm (6 inch). Match the same flange on your inline fan and ducting. Price was £169.99 on the raw scrape.
Does the listing state an airflow rating?
The bullets give 388 CFM (listing).
How strong is the amazon.co.uk review line?
The listing line is 4.6 out of 5 from 194 ratings. The raw file contains 0 reviews tagged United Kingdom; treat non-UK text as secondary.
Mars Hydro’s 4 inch filter and pre-filter is the lowest price in this scrape at £27.92, with 4.5 from 148 ratings and 12 UK-tagged reviews in the raw file. Bullets quote 210 CFM, the same airflow number as the AC Infinity 100 mm filter, and they claim 1050+ virgin Australian charcoal. The captured weight is 2.72 kg. The review count does not match the AC Infinity line: 148 ratings against 9,697, so you are buying the diameter and the CFM claim, not the same evidence base. A 60 cm propagation tent with a 100 mm fan is the case UK guides still allow; a 120 × 120 × 200 cm tent is the case they move to 150 mm. Saturation after roughly twelve to eighteen months of continuous running is a shop rule of thumb for carbon filters in general, not a lab result for this ASIN. Choose it when the £20 gap to the top-pick AC Infinity matters more than review depth, and keep the pre-filter on so dust does not reach the bed early.
Pros
Cons
Best for: You want the cheapest 100 mm filter-and-sleeve in this scrape for a small tent you have already measured.
Less suitable: You are ventilating a 120 cm or larger tent, or you want the deeper AC Infinity review file.
Specifications
Common questions
What duct size is the MARS HYDRO listing?
The title and bullets point to 100 mm (4 inch). Match the same flange on your inline fan and ducting. Price was £27.92 on the raw scrape.
Does the listing state an airflow rating?
The bullets give 210 CFM (listing).
How strong is the amazon.co.uk review line?
The listing line is 4.5 out of 5 from 148 ratings. The raw file contains 12 reviews tagged United Kingdom; treat non-UK text as secondary.
Mars Hydro’s 6 inch filter and pre-filter is listed at £40.38 with 4.5 from 148 ratings and 12 UK-tagged reviews. The bullets quote 410 CFM, the same figure as the AC Infinity 150 mm filter, at about £25 less in this scrape. The review base stays in the low hundreds rather than 9,697, so the airflow claim is not backed by the same volume of ratings. Listed weight is 2.72 kg, identical to the 4 inch Mars Hydro row, which is light for a 150 mm cylinder if you are planning hangers, so treat mass as the page’s figure and not a checked heft. The 1050+ charcoal line is marketing on the listing. It is the mid-price 150 mm option when you already own the fan and you do not need the AC Infinity review depth that carries the best-value badge. It is still the wrong class for a 200 mm system, and a 100 mm fan will not seal to this flange without a reducer.
Pros
Cons
Best for: You want a 150 mm filter with a stated 410 CFM and you will spend about £40 rather than £66.
Less suitable: You want the deepest review file, a kit with a fan, or an 8 inch duct.
Specifications
Common questions
What duct size is the MARS HYDRO listing?
The title and bullets point to 150 mm (6 inch). Match the same flange on your inline fan and ducting. Price was £40.38 on the raw scrape.
Does the listing state an airflow rating?
The bullets give 410 CFM (listing).
How strong is the amazon.co.uk review line?
The listing line is 4.5 out of 5 from 148 ratings. The raw file contains 12 reviews tagged United Kingdom; treat non-UK text as secondary.
The AC Infinity AC-DCF8 is the only 200 mm filter in this set, listed at £119 with 4.4 from 305 ratings. Bullets mention premium Australian activated carbon and a pre-filter, and they do not state a CFM figure in this capture. Two UK-tagged reviews is a thin sample, so the 4.4 line should not be read as British consensus. UK shop guides point 200 mm duct at long or walk-in tents and high airflow, not at a 60 cm cupboard. The technical block prints a weight of 454 g, which is not a credible mass for an 8 inch carbon cylinder, so do not size brackets from that figure. Buying this flange also means a 200 mm fan and duct; a reducer down to 150 mm adds the resistance sizing blogs tell you to avoid. It is the row for a system that is already 8 inch, and a poor default if your tent maths still lands on 100 mm or 150 mm.
Pros
Cons
Best for: Your fan and duct are already 200 mm on a long or walk-in tent.
Less suitable: You are sizing a 60–120 cm tent, or you need a stated airflow and a solid UK review sample.
Specifications
Common questions
What duct size is the AC Infinity listing?
The title and bullets point to 200 mm (8 inch). Match the same flange on your inline fan and ducting. Price was £119.00 on the raw scrape.
Does the listing state an airflow rating?
No CFM or m³/h figure is on the bullets we captured. Size the fan first, then pick a filter rated at or above that airflow.
How strong is the amazon.co.uk review line?
The listing line is 4.4 out of 5 from 305 ratings. The raw file contains 2 reviews tagged United Kingdom; treat non-UK text as secondary.
HG Power’s 4 inch filter is listed at £29.99 with 4.4 from 64 ratings, and the title prints Ø100 mm × 200 mm, so the flange is 100 mm and 200 mm is the body length. Ten reviews in the raw file are tagged United Kingdom. Bullets describe a 38 mm bed of Australian virgin charcoal and a pre-filter, and the title also names 3D printer enclosures alongside tents and hydroponics. No CFM figure is on the bullets we captured, so you cannot check contact time against your fan from this page alone. The price sits with Mars Hydro’s 4 inch at £27.92 and Hon&Guan at £29.99, far below the AC Infinity 100 mm at £47.99, with a much smaller review base. It is a plausible spare for a cupboard tent or a printer cabinet that already uses 100 mm duct. It is the wrong buy for a 120 cm tent that UK guides put on 150 mm, and the charcoal wording is listing language rather than a measured odour test.
Pros
Cons
Best for: You need a cheap 100 mm cylinder for a small tent or a printer cabinet and you accept a short review file.
Less suitable: You need a stated CFM, an 8 inch run, or the review depth of the AC Infinity 100 mm filter.
Specifications
Common questions
What duct size is the HG listing?
The title prints 4 inch and Ø100 mm × 200 mm. The flange to match is 100 mm; 200 mm is the body length on that title, not an 8 inch duct. Price was £29.99 on the raw scrape.
Does the listing state an airflow rating?
No CFM or m³/h figure is on the bullets we captured. Size the fan first, then pick a filter rated at or above that airflow.
How strong is the amazon.co.uk review line?
The listing line is 4.4 out of 5 from 64 ratings. The raw file contains 10 reviews tagged United Kingdom; treat non-UK text as secondary.
HG Power’s 6 inch filter is listed at £33.99 with 4.4 from 64 ratings and 10 UK-tagged reviews. The title prints Ø150 mm × 200 mm, so the flange is 150 mm and the 200 mm figure is a short body length, not an 8 inch duct. Bullets again cite a 38 mm Australian charcoal bed and a pre-filter, and they mention 3D printers as well as tents. No CFM is stated, unlike the Mars Hydro 6 inch at £40.38 and the AC Infinity 150 mm at £65.99, both of which print 410 CFM. You are buying the 150 mm class cheaply and giving up a stated airflow plus a deep review file. It suits a matched 150 mm fan when the budget is tight and you will replace the cylinder when odour returns. It does not suit an 8 inch run, and a 200 mm body is short contact time you cannot verify without an airflow rating.
Pros
Cons
Best for: You already have a 150 mm fan and you want the lowest 6 inch shelf price here.
Less suitable: You need a stated airflow, an 8 inch duct, or the AC Infinity review base at £65.99.
Specifications
Common questions
What duct size is the HG listing?
The title prints 6 inch and Ø150 mm × 200 mm. The flange to match is 150 mm; 200 mm is the body length on that title, not an 8 inch duct. Price was £33.99 on the raw scrape.
Does the listing state an airflow rating?
No CFM or m³/h figure is on the bullets we captured. Size the fan first, then pick a filter rated at or above that airflow.
How strong is the amazon.co.uk review line?
The listing line is 4.4 out of 5 from 64 ratings. The raw file contains 10 reviews tagged United Kingdom; treat non-UK text as secondary.
Hon&Guan’s 4 inch filter is listed at £29.99 with 4.0 from 259 ratings, the lowest star line in this comparison, and 39 UK-tagged reviews, the largest UK subsample in the raw files. The title prints Ø100 mm × 200 mm and includes a pre-filter; bullets quote 267 CFM and 1200+ IAV RC 48 charcoal, and they mention 3D printers. That CFM claim sits above the 210 CFM on the AC Infinity and Mars Hydro 100 mm rows, at a similar shelf price to those budget cylinders, with weaker stars. The scrape notes say to read the UK texts for odour and fit rather than trust the star average alone, and this file is where that advice has the most reviews to read. It remains a 100 mm flange with a 200 mm body, so it does not become an 8 inch filter because the length number looks large. A cupboard tent or a printer enclosure on 100 mm duct is the plausible use; a 120 cm flowering tent is the sizing mistake. Against Mars Hydro’s 4 inch at £27.92 and 4.5 stars, the Hon&Guan row is neither the cheaper pick nor the higher-rated pick, so the reason to choose it is the larger UK review sample and the higher listed CFM, which remains a bullet rather than a lab test.
Pros
Cons
Best for: You want a £30 100 mm filter and you will read the larger UK review sample before you trust the 4.0 line.
Less suitable: You want the highest stars at this price, a 150 mm tent, or an 8 inch system.
Specifications
Common questions
What duct size is the Hon&Guan listing?
The title prints 4 inch and Ø100 mm × 200 mm. The flange to match is 100 mm; 200 mm is the body length on that title, not an 8 inch duct. Price was £29.99 on the raw scrape.
Does the listing state an airflow rating?
The bullets give 267 CFM (listing).
How strong is the amazon.co.uk review line?
The listing line is 4.0 out of 5 from 259 ratings. The raw file contains 39 reviews tagged United Kingdom; treat non-UK text as secondary.
Eleven amazon.co.uk listings, shelf date 20 October 2026, are on this page. There is no laboratory odour test. Amazon evidence is 40 points, fit for the duct and the kit is 35, and value in GBP is 25. Global-heavy star lines are marked down when UK-tagged reviews in the saved file are thin. The highest total is the top pick, once. The strongest value score that is not that row is the best value, once. On the cards those are the AC Infinity 100 mm filter and the AC Infinity 150 mm filter.
Amazon evidence
40%Star rating scaled by review count. Global-heavy listings are marked down when UK-tagged reviews in the saved file are thin. Repeated themes such as the wrong diameter, odour leak and carbon dust reduce this block.
Fit for the job
35%Stated duct class, listed airflow on the bullets, the carbon claim, a pre-filter mention, and whether the row is a matched fan-and-filter kit.
Value
25%Shelf price in GBP against evidence and diameter. The cheapest 100 mm row does not win if tent sizing guides point to 150 mm for that footprint.
Match the flange to the fan, then check that the filter’s listed airflow is at least the fan’s. A lower price on the wrong diameter does not fix a 120 cm tent.
A carbon filter in this comparison is a metal cylinder of activated charcoal on the extract duct of a grow tent or a small enclosure. The inline fan pulls tent air through the bed so odour is reduced before the air leaves, provided the flange matches the fan and the filter’s listed airflow is at least the fan’s. This amazon.co.uk batch, read in October 2026, is eleven listings. It is not a census of UK shops, and it is not a laboratory odour test.
UK guides move a 120 cm tent to 150 mm. A cheaper 4 inch cylinder is the wrong flange, not a bargain on that footprint.
Size the fan from tent volume, then pick a filter rated at or above that airflow. A missing CFM bullet is not a pass.
Mixing 100 mm, 150 mm and 200 mm, or crushing flex duct, adds the resistance the duct guides tell you to avoid.
Several listings show thousands of ratings. The saved files hold far fewer reviews tagged United Kingdom. Read those texts for odour leak and carbon dust.
Use one diameter for the fan, the filter and the duct: 100 mm, 150 mm or 200 mm. A cupboard or 60 cm tent often stays on 100 mm. A 120 × 120 × 200 cm tent, about 2.9 cubic metres, is the case UK guides move to 150 mm. 200 mm is for long or walk-in tents. On the HG Power and Hon&Guan titles, 200 mm is body length, not an 8 inch flange.
After the fan is sized, the filter’s listed CFM should be at least that fan. Bullets here quote 210, 267, 352, 388 or 410 CFM, or they quote nothing. Charcoal grades are listing language. Star lines such as 4.7 from 9,697 are mostly global. The saved UK-tagged texts are the part to read before you trust the score. Replace a clogged pre-filter, and plan on a new cylinder when odour returns, often quoted as twelve to eighteen months of continuous use.
Three typical situations, each with a recommendation from this comparison.
Your volume maths stays on a small cupboard or a 60 cm tent, and the fan is already 100 mm. The AC Infinity 100 mm filter is about £47.99, with a 210 CFM bullet and the deepest review file in this set. It is the wrong flange if the tent is already in the 120 cm class.
UK guides commonly put a 120 × 120 × 200 cm tent on 150 mm duct. The AC Infinity 150 mm filter is about £65.99, with a 410 CFM bullet, and it is the best value here if you already own the fan. A cheaper 100 mm cylinder does not change that diameter.
You want the fan and the filter in one 150 mm box. The VIVOSUN G6 is about £169.99, with 388 CFM and smart control on the listing. The AC Infinity CLOUDLINE LITE kit is about £189 with 352 CFM and no app. Neither row has UK-tagged reviews in the saved file.
Eleven amazon.co.uk carbon filters are on this page, and none was odour-tested in a lab. The AC Infinity 100 mm filter, about £47.99, is the top pick: 4.7 from 9,697 ratings, a 210 CFM bullet, and the strongest review file for a small 100 mm tent. The AC Infinity 150 mm filter, about £65.99, is the best value: the same rating pool, a 410 CFM bullet, and the 150 mm class UK guides use on a typical 120 cm tent. A kit near £170 to £189 only pays if you still need the fan.
AC Infinity 100 mm carbon filter
Strongest review file in the set, 4.7 from 9,697, on a 100 mm flange with a 210 CFM bullet at about £47.99.
AC Infinity 150 mm carbon filter
150 mm filter-only at about £65.99 with a 410 CFM bullet, the duct class UK guides use on a typical 120 cm tent.
Editorial
Peter F. is the editor for DIY & tools at productscompared.co.uk. Comparisons in this category are checked against amazon.co.uk listings, review evidence and public UK sources.
Guides on what to look for, how to use a product, and common mistakes.
Public UK sources for sizing, licensing and electrical safety, last checked on 20 October 2026. Amazon.co.uk listing lines are the price and review source for the eleven ASINs. No laboratory odour test was run.
This article contains affiliate links. If you buy through these links, we may earn a commission at no extra cost to you. The cards use amazon.co.uk listing data and public UK sources. They are not a laboratory test.
