15
Water Action Volunteers – Level 2 Manual
Updated January 2016
Oakton Acorn pH 5 and 5+ Meter
WAV volunteers currently use one of three different pH meters:
1. pH 5 (original software and original outside casing)
2. pH 5 (updated software, but original outside casing)
3. pH 5+ (updated software and updated outside casing)
pH 5 meter
pH 5+ meter
Which pH meter do I have?
Before calibrating your pH meter, you will first need to ascertain which meter version you are
using. This information is important to know because the calibration protocol is varies slightly
between the different software versions.
The only way to tell if you have meter version #1 or #2 is by going through the calibration
process and seeing what happens between the calibration with the pH 7 buffer solution
calibration and the calibration with the pH 10 buffer solution. The original software tells the
meter to exit calibration mode and return to measurement mode upon completion of the first
calibration point. This means that you will complete two ‘one point’ calibrations as you have to
re-enter calibration mode in order to complete the pH 10 calibration. The software update on
the newer meters keeps the meter in calibration mode throughout the calibration process (the
values on the screen will continue to blink). This means that you will complete a ‘two point’
calibration when calibrating the meter.
For all meters used by WAV volunteers…
Both the Oakton Acorn pH 5 and the 5+ meters need to be calibrated before being used in the
field each and every time you monitor throughout the field season. Once calibrated, the pH
meter can be turned on and off between monitoring events if you monitor at multiple locations
in one day (unlike the DO meter).
When calibrating your meter, please use both the pH 7 and pH 10 buffer solutions (NIST)
provided in order to calibrate the meter. Do not reuse the buffer solutions following the
calibration as contaminants in the solution can impact the accuracy of the calibration and the
field measurements.
