Bluelab Truncheon Meter - Manual (Page 5)

Information about the scales available on the
Bluelab Truncheon
® Nutrient Meter
CF and EC
CF and EC are measures of electrically charged nutrient ions in a solution.
Pure water will not conduct electricity. Water usually conducts electricity because it
is full of impurities, in our case, electrically charged nutrient ions. The two black dots
on the end of a nutrient probe are called electrodes. When these are placed in a
solution, an electrical current passes from one electrode, through the water to the other
electrode and counts the number of electrically charged ions present. This represents
the units measured - EC or CF.
ppm measures parts per million
There are many different scales used for different industries around the world and
for many different reasons! Did you even know there are more than two scales? The
most widely used scales in Hydroponics are the 500 scale, 650 scale and the 700 scale.
What’s the difference?
The ppm 500 scale is based on measuring the KCl or potassium chloride content of
a solution. The ppm 700 is based on measuring the NaCl or sodium chloride content
of a solution. Individual nutrient ions have different electrical effects! The true ppm of
a solution can only be determined by a chemical analysis. ppm cannot be accurately
measured by a CF or EC meter.
They are present on Bluelab products as a conversion guide only.
The conversion is as follows;
2.4 EC x 500 = 1200 ppm (500 scale) or 1200 ppm / 500 = 2.4 EC
2.4 EC x 700 = 1680 ppm (700 scale) or 1680 ppm / 700 = 2.4 EC
If you are wanting to measure your solution in ppm, you will need to know the
following:
• What ppm scale is your meter using?
• Which calibration standard should you use for your meter?
• What ppm scale is your nutrient referring to?
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