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G.A.S Intelligent Humidity Controller

Only 3 left
SKU: 133385
Regular price £249.99

G.A.S Intelligent Humidity Controller

Optimise nutrient uptake, water absorption & growth - harness your humidity & VPD with a G.A.S Intelligent Humidity Controller & G.A.S SonicAir Pro Humidifier.


Your VPD is the 'drying power' of air - how much pressure it puts on plants to transpire. It's determined by what your humidity is, at a specific temperature.

To optimise your VPD, this controller determines and maintains your ideal humidity, based on:

  • air temperature
  • stage of growth
  • plant temperature
  • light cycle (on / off)

You don't have to worry about temperature fluctuations messing with transpiration. No other humidity controller gives you this much precision.

  • Optimises transpiration, uptake & growth
  • Humidity based on: air temperature, plant temperature, stage of growth & time of day
  • RH (%) or VPD (Vapour Pressure Deficit)
  • 24hr or Day/Night mode
  • 3 VPD settings: Early veg; late veg/early flowering; late flowering

Compatible Humidifier

No extra power supply is needed - your cotroller is powered by your G.A.S SonicAir Pro Humidifier.


There's lots to love...

Precise! Micromanage Your VPD

Your ideal humdity is set and maintained, based on: air temperature, plant temperature, stage of growth & time of day. This ensures nutrient uptake, translocation & plant growth are optimised, at all times.

4 Operation Modes

  • VPD or Humidity
  • 24hr or Day/Night

Overall, there are 4 possible combinations

3 In 1 Probe (Ready Wired)

This senses the temperature, humidity & light on/off times.

Position it in the middle of your grow room, just over the plant canopy.

One Controller, Multiple Variables

No other control automatically manages your VPD. Normally it takes multiple readings from multiple devices, with manual calculations.

No Power Supply Needed

You don't need a spare socket - your controller is powered by your G.A.S SonicAir Pro Humidifier.

Built-In Memory

All settings will be saved if there's a power loss. But you can eaily return to factory settings if and when you want to.

Control Types

  • Relative Humidity 24 hours

It'll maintain your chosen relative humidity 24 hours a day

  • Relative Humidity Day / Nght

This maintains your chosen relative humdity, with one setting for day (lights on) and another for night (lights off) .

  • VPD 24 hours

This calculates your VPD - the 'drying power' of air - based on: air temperature, relative humidity & plant temperature. You will need to specify the stage of growth you're at, and enter a target VPD for each stage of growth. Your ideal humidity is calculated and maintained, based on this.

  • VPD Day / Night

During the day, the controller works as described in 'VPD 24 Hours'. During the night, instead of targetting VPD, your controller monitors & maintains a static relative humidiity. This is because plants don't photosynthesise and don't need to transpire at night. Instead, it's more important to keep your relative humidity low, to prevent mould.

We recommend going for: VPD Day / Night.

What's VPD?

Plants constantly transpire - this is where they lose water. This process directly impacts nutrient uptake, translocation & ultimately growth.

To control transpiration, some growers focus on their humidity. A higher humidity slows it down, a lower humidity speeds it up. The problem is, at different temperatures, your humidity has a different affect on transpiration,.

To really know how your humidity affects transpiration, you need to monitor your VPD (vapour pressure deficit).

Think of your VPD as the drying power of air. It uses your temperature & humdity (%RH) to calculate the transpiration pressure placed on plants.

  • A high VPD means the air is dry, so water leaves plants at a faster rate
  • A low VPD means the air is moist, so water leaves plants at a slower rate

Remember, moisture moves from wetter areas to drier areas. The bigger the gap, the faster this happens. Kind of like how a drier sponge takes less time to soak up a spill then a damp one.

Target VPD:

Early Veg: 0.4 - 08 Kpa
Plants are young and don't have a strong root system to replace water lost through leaves - you want a higher VPD to slow transpiration.

Early Flowering: 0.8 - 1.2 Kpa
Plants have more leaves and more roots, so you can go slightly lower your VPD to speed up transpiration.

Late Flowering: 1.2 - 1.6 KpA
At this point, plants are well established. Extra water uptake is helpful, and a drier air temperature helps ward off pathogens and diseases (e.g. bud rot).

VPD ChartVPD Chart

How To Use

This controller is designed for use with the G.A.S SonicAir Pro Humidifer.

1. Place The Probe

Place it in the centre of your grow room, above the canopy, under any lights (the probe will need to sense whether they're on or off for day/night mode).

2. Connect To Humidifier

Connect the controller to your humidifier using the male/male lead (included).

Plug your humidifier into a socket - the controller is powered by the humidifier.

3. Set Controller

Everything is set using the large 'Menu' dial.

  • Turn to the right to select menus and change values
  • Press to select or open menus

When you first turn the controller on, you will be on the home screen:

1 Turn the controller to the right to show default settings

2. Press the dial to open the main menu

3. Turn the dial to move through menu items

4. Select items from the menu by pressing the dial

4. Probe Calibration

The probe comes pre-calibrated, however you can recalibrate it to offset the temperature or humidity.

To do this, enter the main menu, scroll to 'probe calibrate' and select it.

5. Leaf Temperature Offset

There's an option to enter a 'leaf temperature offset'. This is how much lower your leaf temperature is than your grow room temperature. We recommend an offset of '-1' for small plants, or '-2' for bigger plants.

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