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Bluelab Nutrient (CF) Truncheon

Bluelab Nutrient (CF) Truncheon

from £74.95

Bluelab (NZH) Nutrient (cF) Truncheon

Code: 121

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Forget the guesswork! Never overfeed or underfeed plants again. All you need is a Bluelab CF Truncheon.

It’s easy to useeasy to read and extremely accurate. No wonder it’s the world’s bestselling conductivity meter.

Using one is completely fuss freeNo calibrating is needed and there are no switches or knobs to faff with. To take a reading, you just place the probe head straight into your solution – it switches on and off automatically!

• Bluelab CF Truncheon 
• 12 month warranty included
• Easy to use and read
• Comes factory calibrated - no need to recalibrate it (ever)
• Automatic on/off function
• No switches, dials or knobs
• Fully waterproof
 Meter length: 40.7cm or 16 1/32 in.

The Science

Nutrient strength is measured in EC (electrical conductivity) or CF (conductivity factor). 

1 CF is the same as 0.1 EC. Really, they tell you the same thing – how many dissolved salts are in your solution.

So the stronger your feed, the higher the CF/EC reading will be.

If your CF is too low, plants may not be getting enough nutrients. If it’s too high, plants can dehydrate.

The best nutrient strength to aim for depends on how hard your water is and what stage of growth you’re at. As a rough guideline, aim for:

• Young plants = 6 – 12 CF (0.6 - 1.2 EC)
• Establishing plants = 10 – 16 CF (1.0 - 1.6 EC)
• Mature plants = 15 – 20 CF (1.5 - 2.0 EC)

How to Use

To measure conductivity, place the probe into nutrient solution and take reading as indicated by the flashing lights.

If the lights are dancing between two values, the reading is between those two values (e.g. lights dancing between ‘6’ and ‘8’ indicates a reading of ‘7’)


For very cold or very hot temperatures it will take 1-2 minutes for the probe to reach solution temperature.

To help decrease time taken to reach the solution temperature, place the probe in an area where there is lots of movement.


We recommend the probe be cleaned once every two weeks according to the cleaning and maintenance instructions provided with your meter. This can vary depending on frequency of use.

Q & A

Questions and Answers (3)

Hi I just want to check I'm measuring my cf level correctly. Are you supposed to measure the cf level of your tap water, then add that to the recommended cf level on the feed chart. Or should the finished nutrient solution be what it says on the chart. Thanks
Hi Joe, it's best to leave your tap water to stand for 24 hours to allow the chlorine to dissipate, then take the CF reading. You would take the reading as the baseline - if your water's CF measures 2, you should aim for a reading of 18 to achieve a nutrient strength of 16. Thanks

Written by Joe | 16 Mar 2017

i was led to believe that the truncheon was an all in one reader but does not mention ph is a ph reader needed as most tap water is neutreul
The Bluelab cF truncheon will measure the amount of nutrient in the solution, you also need to check the pH & adjust if required. Optimum pH for your nutrient solution is 6.2, but it is fine between 5.8 -6.8

Written by paul | 28 Nov 2012

when your ready to harvest and your flushing what should the reading be? and if i take a reading when im growing how will i know om giving it the correct amount of feed is there a chart or something telling you does it give you the reading on the truncheon?
The cF whilst flushing should be the same as your tap water, typically 2 in soft water areas, 8 in hard water areas. During the Growth cycle you can always refer to the chart in the back of our catalogue, but remember to check against your level of water hardness.

Written by karen | 14 May 2011