Bluelab Combo Meter - Manual (Page 4)

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4
3.0 Calibration
pH calibration is required before fi rst use to ensure that the fi rst reading is accurate.
• The Bluelab Conductivity/Temperature Probe DOES NOT require calibration.
• The pH of the Bluelab Combo Meter DOES require calibration.
For accurate pH readings the pH probe is cleaned and recalibrated when:
• The reading is different to what you were expecting.
• The batteries have been removed or changed.
• The pH probe is replaced with a new one or is disconnected from the Combo Meter.
• The pH calibration indicators have disappeared.
When calibrating the pH after fi rst use the pH probe needs to be cleaned. See pH probe
cleaning in section 8.0.
For best pH calibration
pH reading accuracy is dependant on the accuracy and age of the calibration
solutions used, and use and cleanliness of the pH probe tip.
• Ensure the pH probe has been cleaned and rinse the pH probe with clean water
between calibration solutions to reduce contamination of the pH solutions.
• Only fresh uncontaminated solutions should be used.
• Calibrate the pH at the same temperature as the solution to be measured.
• ALWAYS calibrate the pH probe with pH 7.0 then pH 4.0 or pH 10.0.
NOTE: The conductivity/temperature probe does not need to be calibrated, but must be
cleaned to remove any build up of nutrient salts. See Section 7.0.
The pH calibration involves cleaning the pH probe tip and then calibrating in
TWO SOLUTIONS.
If a reading below pH 7.0 is expected, use pH 7.0 and pH 4.0 calibration solutions.
If a reading above pH 7.0 is expected, use pH 7.0 and pH 10.0 calibration solutions.
Follow the steps on the following page for Combo Meter pH calibration.
Storage and use of calibration solutions
• Always place the lid back onto the bottle after use or evaporation will occur rendering
the solution useless.
• Store in a cool place.
• DO NOT measure directly into the bottle. Tip a small amount into a clean container
and discard after use.
• Never add water to solutions.
pH reading accuracy is dependant on the accuracy
and age of the calibration solutions used, and use
and cleanliness of the pH probe tip.