Bluelab Soil pH Meter - Manual (Page 4)

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4
3.0 Calibration
pH calibration is required before fi rst use and then monthly to ensure readings are
accurate.
For accurate pH readings the soil pH probe is cleaned and recalibrated when:
• The reading is different to what you were expecting.
• The batteries have been removed or changed.
• The soil pH probe is replaced with a new one or is disconnected from the soil pH Meter.
• The pH calibration indicators have disappeared.
When calibrating the pH after fi rst use the soil pH probe needs to be cleaned. See soil
pH probe cleaning in section 8.0. The soil pH probe does not need to be cleaned for
initial calibration.
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 soil pH probe tip.
• Ensure the soil pH probe has been cleaned and rinse the soil pH probe tip 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 soil pH probe with pH 7.0 then pH 4.0 or pH 10.0.
The pH calibration involves cleaning the soil 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 below for soil pH meter 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 soil pH
probe tip.