Bluelab Meters and Monitors

Understanding the nutrient solution is an important part of successful growing. Growth Technology’s accurate range of Bluelab meters and testing equipment make this task quick and easy.

Bluelab Guardian Monitor

In just one glance it measures all three critical parameters for successful growth; pH, conductivity AND temperature.

The Bluelab Guardian Monitor is a constant indicator of the desired levels of EC/ppm 700/TDS/CF, pH and temperature, enabling the grower to optimise these parameters as the crop progresses through each growing phase.

The Bluelab Guardian Monitor is mains-powered and is mounted to the wall or hung on a support and the probes simply placed into the reservoir.

With the Bluelab Guardian Monitor monitoring the crops 24 hours a day and with the ability to set high and low alarms, a flashing display indicates if one parameter moves away from the ideal, allowing the required adjustments to be made, quickly and effectively.



  • Plant-safe green LEDs
  • Large easy to read displays
  • No calibration required for conductivity and temperature
  • Simple push button pH calibration
  • Selectable values for conductivity and temperature
  • Flashing high and low alarms
  • Greater tolerance to RF / electronic interference provided
  • Water resistant design
  • International power supply
  • Replaceable double junction pH probe
  • Adjustable display brightness
  • Non-volatile memory


bluelab 2 year..



Bluelab will show how to set up the Bluelab Guardian Monitor for the first use, calibrate the pH probe, take readings and use the ‘quick set’ alarm function.


Bluelab’s video will show how to clean and calibrate the pH probe, plus clean and test the conductivity/temperature probe for the Bluelab Guardian Monitor.

  • Mount the Guardian Monitor in a clean dry place out of direct sunlight.
  • Clean the pH and conductivity probes at least monthly, or even more often if using additives or nutrient solutions that contain oils, as these contaminate the probe and give an inaccurate (low) reading.
  • Calibrate the pH every time you clean the pH probe which should be monthly, and use only fresh calibration solutions each time. Large bottles of calibration solution are de-cantered into smaller containers. This stops contamination of the solution.
  • Be gentle with the pH probe as it is made of glass and is easily broken.
  • Submerge both the pH and conductivity probes into the tank/reservoir, as these are waterproof.
  • Place the conductivity probe into the pH calibration solution with the pH probe to ensure temperature compensation is available during calibration. The temperature reading is available via the conductivity probe only.
  • Replace the pH probe when it is giving unusual readings or is over 12 months old. pH probes do not last forever and age through normal use and will eventually fail.
  • Replace the pH probe wetting cap, filled with fresh water or 4.0 pH solution, back over the tip of the pH probe when not in use. This stops the pH probe from drying out. If it dries it dies!
  • Always place the plastic shroud of the conductivity probe back onto the probe tip after cleaning to protect the probe face and ensure accurate readings.
  • Wait 5 – 10 minutes for the reading to stabilize if the probe temperature is very different to the temperature of the solution.
  • Don’t be rough with pH probe or bang it on the side of the tank – it will break!
  • Don’t touch the pH or conductivity probe tips with fingers or it will contaminate the probe surface. The only time the conductivity probe can be touched is when cleaning the probe with the liquid scourer. Use a Bluelab Chamois to clean the conductivity probe when available.
  • Don’t throw away the Instruction Manual – keep it in a safe place so it can be referred back to, if needed. The cleaning and calibration instructions are in the manual and should always be referred to until the grower is confident that the procedure is being carrying out correctly.
  • Don’t open the Monitor, as there are no user adjustments inside. This will void the guarantee.

Why is pH important for my plants?

The two main effects the pH level has on plant growth are related to the availability of plant nutrients or the soil concentration of plant-toxic minerals. Within highly acid soils, micronutrients, such as aluminium and manganese, can become more available and therefore more toxic to the plant. Equally affecting growth when there are low pH values, calcium, phosphorus and magnesium are less available to the plant. Read more.


Plant Lifecycle

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