A speed controller adjusts extractor output without relying on a sensor: you pick the speed, the unit holds it. It is the most direct way to cut installation noise, reduce power draw and match air changes to the growth stage.
Manual, fixed-speed or automatic
The simplest models offer a dial or a set of preset speeds: the setting stays put until you change it. Others add an automatic mode that modulates ventilation according to ambient temperature, while keeping manual override available when the situation calls for it.
Sizing the current rating
The deciding factor is the current rating in amperes: it must cover the combined draw of everything connected to the controller. An undersized unit heats up and trips; a generously sized one causes no problem at all.
Minimum speed and noise comfort
Slowing an extractor cuts its noise sharply, but every motor has a threshold below which it hums or struggles to start. Controllers with a minimum-speed setting let you fix that floor once and for all.