FAQ and troubleshooting for the Bluelab Truncheon Nutrient Meter

Find answers and solutions to common questions

General questions

Does the Bluelab Truncheon need calibrating?  

Conductivity meters like the Bluelab Truncheon do not require calibration as they are factory calibrated.  

Why is my Truncheon reading lower than I expect?  

Nutrient solutions, fertilisers and salts can build up on your conductivity probe and cause the Truncheon to read lower than you might expect. We recommend cleaning and testing your Truncheon in 2.77EC Conductivity Standard at least once every month to remove residue.  Make sure you are not taking a measurement in RO, deionsed or distilled water, as testing in this type of water won't register on the Truncheon. See this guide for more on RO water

Follow the troubleshooting guide below for more on inaccurate readings. 


Troubleshooting guide


Trouble Possible reasons Correction
Truncheon is reading low or not accurate. Dirty probe head. The carbons on the probe head are easily contaminated with oils and greases, for example, from fertilisers and organic nutrients, and even your fingers. Try not to touch the probe head for this reason. Clean the probe heads by following the conductivity probe cleaning guide
Temperature. Errors in reading can occur if the solution is hotter or cooler than the probe head.   Wait for the probe to come to the same temperature as the solution. Keep the probe in the solution for 1-2 minutes. 
Shroud may be missing or loose. Ensure the shroud is on correctly. 
Measurement is taken in RO, distilled or deionised water. Only measure solutions with 200 ppm or higher. Anything less will not return a reading. Read the guide on RO water for more.

Truncheon LEDs aren’t flashing when immersed in solution, or flashing is intermittent.

Solution conductivity is lower than 0.2EC. 

The Truncheon will not turn on if the conductivity of the solution is not higher than 0.2EC. Add more nutrients to your solution and re-test. 

Flat battery. Battery life will depend on the amount of use.  

If the Truncheon fails to illuminate any LEDs when immersed in solution, the batteries should be changed.  

Corrosion of battery contacts. Corrosion can occur if there is a battery leak, or the battery chamber has been wet.  

It can be difficult to remove corrosion from the battery cap spring. If corrosion is noted on the battery cap spring or the battery contact, and it is causing intermittent readings, consider replacing the Truncheon.
Water ingress.

Water getting into the battery unit. Never leave the Truncheon in the reservoir.  

Take the cap off and remove the batteries. Shake as much water out as possible.  

Then, leave the Truncheon in a warm, dry place with the cap removed to allow it to dry out. Ensure the O-ring is present and intact. If corrosion is noted, consider replacing the Truncheon.  

Missing or damaged cap O-ring.  


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