Methods

pH

      This page will outline how to take a pH reading from a water sample using the Waterproof pHTestr2 from Oakton Instruments:

Calibration

      Before sampling with the pHTestr2, the user should consider calibrating the probe. This will ensure accurate and consistent results each week.

      In order to calibrate the probe, we will use a one-point calibration with the 7.0 buffer solution. From our observations, this is just as acceptable as using a three-point calibration using three buffer solutions.

      Pour enough of the 7.0 buffer solution into a clean beaker to cover the electrode portion of the probe. Remove the cap from the probe and press the 'On/Off' button once to turn the probe on. After 'PH' flashes off of the display, place the electrode portion of the probe into the solution. It will begin to read the solution on the display. Once the reading on the display gets near the 7.0 mark, press the 'CAL' button once. It will continue to read the solution, but the numbers in the display will flash once every second. After at least 30 seconds, press the "Hold/Con" button. It will store the calibration information in the probe. It should now be calibrated and read 7.0 on the display when in the 7.0 buffer solution. You can now turn the probe off by pressing the 'On/Off' button once. It will store the calibration information even when turned off. In fact, it will store it until either the calibration process is performed again or the batteries are replaced. Remember to never pour the used buffer back into the original bottle. The used buffer can be saved in a separate air-tight container and will work for weeks.

Sampling

      After the probe is calibrated it is ready to take pH measurements. Simply turn the probe on by pressing the 'On/Off' button once and wait for 'PH' to clear from the display. Take the protective cap off of the electrode end of the probe and place into the sample and stir gently for a few seconds. Give the probe time to settle on one reading; this may take a few minutes, but usually occurs quickly. When the sampling procedure is over, rinse the electrode area of the probe with clean water and replace the cap. Make sure to turn off the probe before packing it away for the week. It will drain the batteries if this step is skipped.