Getting started: The Bluelab pH In-line probe

Product overview, quick start guide and FAQ


The Bluelab pH Probe In-line is a double-junction probe for your Bluelab Guardian Monitor Connect In-line. Use this probe to measure pH accurately directly in your nutrient line. 


Double-junction reference 3/4” NPT thread fits inline mounting; use with 1” adapter
Fully waterproof, including cable joint Pressure rating of 7bar pressure or 100 psi
3-metre / 10-foot cable  1-year warranty

Quick start guide 

Before you use your In-line Probe: 

  1. Attach the In-line probe to the meter via the BNC fitting (metal end). 
  2. Remove the storage cap. Hold the cap and twist the base one full turn, then gently remove. Salt crusting on the probe is normal. 
  3. Calibrate your probe to your Bluelab meter, monitor or controller by following the instructions on the back of the probe. Read more on how to calibrate your probe.

Recommended installation of in-line probes 

Installing the Inline pH probe
The probe works best when installed vertically downwards at the bottom of a loop. This helps to keep the probe tip above sediment, and the air bubble within the probe itself - away from the tip. The probe tip should not be allowed to dry out, installing at the bottom of a loop will ensure there is solution filling the pipe to keep the probe hydrated.

Installing the Inline Conductivity probe
The Conductivity probe works best when installed horizontally. This helps to keep the probe tip clear of sediment and prevents air bubbles gathering in the probe shroud. The Probe shroud is required to limit the electric field to create a consistent and accurate reading.


  • A minimum flow rate of 2 ft/s (0.6 m/s) will help prevent sediment build up on the probe head.
  • Ensure the probes are securely tightened into the pipe fittings. Thread tape is recommended to protect the PVC threads and prevent leaking.




Quick tips for care

Clean and calibrate your probe at least monthly. Follow the pH probe calibration guide.

Never immerse the probe in proteins or oils. Oils affect the accuracy of the probe as they leave a film on the probe. 

Avoid knocks and sideways force. This could damage the delicate glass inside the probe. 

Further resources 

How to calibrate Bluelab probes

Cleaning Bluelab pH probes (+ video) 

FAQ and troubleshooting guide for Bluelab pH Probes


Still can’t find what you're looking for? Contact Support