G-Tools 125mm Inline Fan with Integrated Speed Controller420 m³/h

The G-Tools 125mm inline fan combines a high-efficiency Swiss MES motor with an integrated speed controller in a single unit. It suits growers running one grow light who want quiet, controllable extraction without buying a separate fan controller.

At 420 m³/h, this fan is well matched to a single-light grow room. As a rough guide, a 1.2 m × 1.2 m tent needs to turn its air over every one to three minutes. This fan handles that comfortably with headroom to spare, even when resistance from ducting and a carbon filter is factored in.

The built-in speed controller is the standout feature here. When lights go off, room temperature can drop sharply. Being able to dial the fan back rather than running it flat-out around the clock saves energy and keeps humidity more stable during the dark period. There is no need to buy or wire in a separate speed controller, which keeps the setup tidy and reduces points of failure.

The backward-curved impeller design is not cosmetic. It genuinely improves static pressure performance, meaning the fan maintains closer to its rated airflow when pushing air through a carbon filter and a metre or two of ducting. Cheaper fans with straight-blade impellers lose far more performance under load. The Swiss MES motor runs cooler and more quietly than budget alternatives at comparable airflow ratings.

Pair this fan with the Prima Klima K2601 125mm carbon filter for odour control - the two are sold together at a permanently reduced price. Use 125mm acoustic ducting between the fan and filter to cut noise further. If your grow room runs warm, mount the fan inside the space drawing air through the filter, then exhaust to a loft or external vent for maximum efficiency.

Grower’s Note: When using the speed controller, avoid running the fan below 40-50% of its rated speed for extended periods. Very low speeds reduce static pressure enough that a carbon filter may not receive adequate airflow to scrub odours effectively. During the lights-on period, run the fan at a higher setting to manage heat; drop it back by one-third during lights-off to maintain gentle air movement without chilling the canopy.

Priced at £189, with free UK delivery.