Fan Speed Controller




  • Plug and play
  • Cost effective controller
  • Manually controls speed of fans
  • Gives you control of grow room temperatures
  • Great build quality
  • Simple to use

It is safe to say that every self-respecting hydroponic grow room will need a fan speed controller. It is highly unlikely that the default fan speed will be suitable for your room. The fan speed controller allows you to manually adjust the rotary speed of your extract or intake fans, getting them to deliver the perfect rate of airflow, every time.


Unlike the variety of more expensive fan speed controllers on the hydroponics market, there is no temperature control probe with this unit. This means there is no need to figure out the most appropriate place in your room to place the probe, simply plug your fan in and adjust until you achieve the desired air flow rates. The dial on the front of the unit goes simply rotates from minimum to maximum, adjusting the fan speed as it turns.

There are a few examples of when it would be practical for an indoor grower to reduce the air flow of their extraction system, most significantly being when it comes to the cooler winter months. With the outside air temperature being extremely low, there is now need to have your extraction fans running on full power, so the simple addition of the fan speed controller provides a simple way to achieve this.

It may be that your intake fan is the same size as your extract fan, and you are running into a situation whereby you have positive air pressure in your room. This is the main cause of un-filtered grow room air escaping to the outside world. Using this manual fan speed controller provides a quick and simple solution to that problem.

The fan speed controller uses a technique called ‘Pulse width Modulation’ to adjust the speed of the fan. Essentially this means it chops up and recreates the electronic signal being delivered to the fan, which in turn rotates the motor at a different speed. This allows the unit to be significantly smaller and cheaper than other fan speed controllers, but can sometimes result in a low-level hum to emanate from the fan. The level of hum will vary from fan to fan, it is often insignificant but always worth checking with the make and model you are going to use it with.


Making use of the fan speed controller is a quick and easy way to manipulate the temperature of your hydroponic grow room. If you have recently witnessed your temperature shooting up to unacceptable levels, all you need do is turn the dial up towards the maximum amount and your fan will increase its rotary speed and exhaust more air, taking the unwanted temperature with it! No confusing buttons or dials to tinker with, one way increases the speed, the other decreases it. Fool-proof.

The maximum level for a typical grow room in the generative (or flowering) period is 28 degrees C. If you regularly go over this temperature, your plants may have issues with adequately being able to cool themselves, and the growth and overall production will suffer as a result. You will see heat stress start from the tips of the leaves downwards, and if nothing is done they will simply die and drop off.

Similarly, going below 20 degrees C may have an impact on slowing down the metabolism of the plant to detrimental levels, leading to poor nutrient uptake which will initially manifest itself as purple coloured stems. If you see this as a symptom, it is likely your fan is exhausting too much air and cooling the room too much, so reduce its airflow accordingly.

Getting the correct temperature in your room is key to achieving a healthy harvest. However, the temperature difference can be also just as significant. Using the fan speed controller to manipulate the temperature difference between the day-time (lights on) hours and night-time (lights off) hours is a highly effective way to steer your plants energy into either vegetative or generative plant growth. Using the controller to create a small temperature difference will promote vegetative growth while creating a larger difference will encourage more generative (flowering) growth.

The fan speed controller is the perfect neat and tidy solution to common problems seen with temperatures in a hydroponic grow room.


It is usually a good idea to oversize the extraction fan for your grow room and use a fan speed controller such as to reduce it down to the correct capacity. This gives you the benefit of the fan itself running at a quieter operating level, but also as a failsafe for the hot summer months when you need to crank it up to deal with the UK’s surprisingly scorching summer months.

Do not use this controller with any fan that either has its own internal fan speed control, or one that operates using more than 300w. This is usually 8” and over, but can vary between brands of extract fan. If you are unsure, please give us a ring, we’d love to help.

Always use a plug socket that is easily accessible. If you plug it in at the back of your grow room behind your irrigation system, it is going to make it extremely tricky to get to and adjust!

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Fan Speed Controller

Fan Speed Controller