Getting Started: The Bluelab Guardian Monitor

Product overview and how to get started

Bluelab Guardian Monitor 1-medium


The Bluelab Guardian Monitor is a continuous indicator of the current levels of EC, pH and temperature of your nutrient solution, enabling you to optimise these parameters as your crop progresses through each growing phase.


Bluelab Guardian Monitor

‘Plant Safe’ green LED display

Visual alarm for both high and low settings

Large easy to read displays

Greater tolerance to RF/electronic interference provided

No calibration required for conductivity or temperature

Water resistant design

Selectable units for conductivity and temperature

International power supply

Simple push button pH calibration

Adjustable display brightness

Replaceable double junction pH probe

Settings retained when power lost (non-volatile memory)

Register your product with Bluelab 

Product Manuals: 

MONGUA User Manual - English

MONGUA User Manual - German Deutsch

MONGUA User Manual - Spanish

MONGUA User Manual - French

MONGUA User Manual - Dutch

Get started: 

To mount:

1. Mount unit on wall or hang on support ensuring probes can reach tank/reservoir.

2. Connect appropriate plug adaptor to power supply. 

3. Connect power supply and Bluelab pH probe into base of Guardian Monitor. 

4. Switch on mains power. 

To set up:

Changing conductivity and temperature units
1. Press and hold conductivity 'units' button. Gua Con

After 3 seconds it will change to the next unit indicated by the glowing LED.
Release button. Repeat step until desired unit is selected.

2. Press and hold Temperature 'units' button. Gua temp

After 3 seconds it will change to the next unit indicated by the glowing LED.
Release button. Repeat step until desired unit is selected.

Select display brightness Gua bright

1. Press and hold the 'display brightness' button while pressing up or down buttons to change brightness.

Calibrate pH Probe for the Bluelab Guardian Monitor:

pH Probe calibration must be done before use. EC probe does not require calibration but both probes need to be in the solution for pH to compensate for temperature.

1. Remove storage cap from the pH probe with a gentle twist.

2. Rinse the tip of both probes in fresh water, shake off excess water. 

3. Place both pH and EC probe in Bluelab pH 7.0 Calibration Solution.

4. Press and hold 'pH cal' button until "PH' and 'CAL' appear. Release button. The pH 7 LED and first indicator will flash, increasing to four, as the unit calibrates. The pH 7 LED will illuminate when complete. 

5. Rinse both probes in fresh water, shake off excess water. 

6. Place the tip of both probes in Bluelab pH 4.0 Calibration Solution or pH 10.0 calibration solution. 

7. Press and hold 'pH cal' button until 'PH CAL' appears. Release button. The pH 4/10 LED and first indicator will flash, increasing to four as the unit calibrates. When finished, the pH 4/10 LED will illuminate. Calibration is complete.  

8. If not placing pH probe into tank/reservoir immediately, place storage cap back on. The pH probe tip must not be allowed to dry out. Hydrate with Bluelab KCl Storage Solution if needed.

After 30 days the LEDs will flash indicating calibration of the pH probe is required. 

Placement of probes:

1. Fit the (optional) pH probe holder to the stem of the pH probe. Do not flex or bend the probe stem as it may break!

2. Place pH probe into tank/reservoir and push suction cup onto side, so the tip stays submerged in the solution and doesn't get knocked around.

3. Place conductivity/temperature probe into the tank/reservoir. 

Both probes can be fully submerged.

To set alarms (optional):

Quick-set for high and low alarm values

1. Adjust tank/reservoir to exact conductivity, temperature and pH level required. 

2. Press and hold 'alarm' button until 'AL H' is displayed in all 3 windows. 

3. Press the 'display brightness' button once. 

4. All 3 windows will display 'Auto' then 'SAVE' will display in Conductivity window.

5. The Alarm LED will glow. 

To set the detailed ‘alarm HIGH’ and ‘alarm LOW’ values refer to the Bluelab Guardian Monitor Manual

Actual values:

Gua actual values

Probe maintenance:

Your Bluelab pH and EC probes need to be cleaned and calibrated regularly to extend life and get accurate measurements. Refer to the following articles:


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