Grow Room Ventilation & Filters
Grow room ventilation pulls hot, stale air out and draws fresh air in. It holds temperature and humidity steady around your plants. Hydroponics UK stocks G-Tools inline extractor fans and Prima Klima carbon filters. Sizes run 125 mm, 160 mm and 200 mm, moving air from 185 to 1650 m³/h. A matched 125 mm fan and Eco carbon filter combo costs £155. A 160 mm 800 m³/h fan and filter set is £229. Always pair a fan with a carbon filter to control odour.
Free UK Delivery
Free delivery on all orders.
Grow Anything, Anywhere
Complete kits for soil-free growing indoors.
30 Days Return
30 day returns on all orders.
Secure Payment
Secure online payments 24/7
How to Size and Build Grow Room Ventilation
Grow room ventilation removes heat, controls humidity and stops odour escaping your growing space. A good system has two parts working together. An inline extractor fan pulls air out, and a carbon filter scrubs that air clean before it leaves the room. Without a filter, the smell of an active grow space carries a long way. With one fitted correctly, your exhaust air is near odourless.
Size the fan to your tent first. Work out the volume in cubic metres by multiplying length, width and height in metres. Then multiply that figure by roughly 60 air exchanges per hour. A 1.2 m by 1.2 m by 2 m tent holds about 2.9 cubic metres, so it needs around 174 m³/h before any losses. Now add headroom. A carbon filter, ducting bends and a dirty filter all add resistance that cuts real airflow. Choose a fan rated 25 to 50 percent above your bare figure. That points most home tents at a 125 mm fan.
Comparing G-Tools Fan and Filter Kits by Airflow
The kits below pair a G-Tools inline fan with a matched Prima Klima carbon filter. Buying them together removes the guesswork of matching flange sizes and carbon volume to fan output. Pick the row whose airflow sits above your sized figure.
| Fan / filter set | Fan size | Airflow (m³/h) | Best for | Price |
|---|---|---|---|---|
| Mini Axial Fan + Eco Filter Kit | 125 mm axial | 185 | Propagators and small cabinets | £83 |
| GT-125 Fan + Eco Filter Combo (Matt's Pick) | 125 mm | 420 | Tents up to 1.2 m, 600 W loads | £155 |
| 125mm 2-Speed Fan + Eco Filter Set | 125 mm | 400 | Medium tents needing quiet running | £179 |
| GT-160 2-Speed Fan + Eco Filter | 160 mm | 800 | Multi-light rooms and large tents | £229 |
Matt's Pick: GT-125 Fan + Eco Filter Combo
Best for: a tent up to 1.2 m running loads to 600 W
Why we rate it: the Swiss MES motor holds close to its rated 420 m³/h even with a loaded filter. The virgin-carbon Prima Klima filter controls odour from day one.
Price: £155
Pairing Fans, Filters, Ducting and Controllers
Match the carbon filter flange to the fan diameter exactly. Any reduction at the filter inlet becomes the biggest restriction in the circuit. Fit the filter on the intake side so air is pulled through the carbon bed, not blown. Use solid ducting where you can, keep bends gentle, and seal every join. A short, straight run is quieter and moves more air than a long route full of kinks.
Control gives you the rest. A two-speed fan lets you drop output on cool nights, which lowers noise and makes the carbon last longer. For finer control, a digital fan controller ramps the fan up and down against a target temperature. Hang the fan on soft straps to stop vibration reaching the structure. Fit a duct silencer if a bedroom or office sits nearby.
In ten years of fitting these systems, the mistake I see most is an undersized fan. Growers then choke it with a filter they never replace. Buy the fan a size up from your bare calculation. Sit the filter on the intake, and swap the carbon once a year. Run on the lower speed where your climate allows it. That keeps noise down and stretches filter life across a season.
- Matt W, Hydroponics UK
Frequently asked questions
Multiply tent volume in cubic metres by about 60. Then add 25 to 50 percent headroom for the filter and ducting. Most home tents up to 1.2 m suit a 125 mm fan.
Yes, if you want to control odour leaving the room. The fan moves air, but only a carbon filter scrubs the smell out before exhaust. Always pair the two together.
It is the air volume a fan moves per hour in cubic metres. A 420 m³/h fan shifts 420 cubic metres each hour. Match this figure to your tent volume and air exchanges.
Inline fans push air through ducting against resistance. Axial fans move large volumes at low pressure and suit open spaces. Use an inline fan whenever a carbon filter and ducting are fitted.
Replace the carbon roughly once a year with normal use. High humidity above 70 percent saturates the carbon faster. Running the fan on its lower speed extends filter life noticeably.
A controller is useful but not essential. A two-speed fan covers most needs. A digital temperature controller holds a target reading and ramps the fan automatically.
Build the rest of your space around steady airflow. Pair your fans with grow lights, set up your plants on grow tables, and keep everything tidy inside fully kitted grow cabinets.