9
12.3 Avoid testing in high (>113°F/ 45°C) or low temperature (<41°F/ 5°C) solutions as it will
cause greater measurement error and damage to the probe. Test your samples and
perform calibration close to room temperature as much as possible.
12.4 Never test oily liquids.
12.5 Make sure the battery cap is completely closed with the O-ring. Otherwise, the
waterproof rating could be compromised.
13 Troubleshooting Guide
Trouble
Reason
How to fix
Cannot
calibrate
Incorrect calibration
order
Power on the tester, calibrate pH 7 first, then pH 4. After pH 4
is calibrated, if you want to calibrate pH 7 again, you need to
reboot the tester
Poor quality standard
solutions
Replace with fresh and clean standard calibration solutions
made by legitimate scientific instrument manufacturers
Contaminated probe
Clean the probe with
Apera’s cleaning solution or detergent
water
Aged probe
Replace the probe
Dried-out probe
Soak the probe in the 3M KCl soaking solution for at least 1
hour
Probe is not fully
submerged in the
solution
Make sure the probe is fully immersed in the solution at least 1
inch deep
Air bubbles around
the sensor
Make a quick stir in the solution to remove air bubbles
Reading is
always slowly
changing,
won’t
stabilize
Contaminated probe
Clean the probe with
Apera’s cleaning solution or detergent
water
Clogged junction
Clean the probe with
Apera’s cleaning solution, then soak it in
3M KCL soaking solution overnight.
Aged probe
Replace the probe
Testing pH of low
iconic strength
solutions like tap
water, drinking water,
RO water
Be patient, wait for 2-5 minutes to reach a fully stabilized
reading. If still not stabilizing, add 1ml of 3M KCl solution to
1000ml of test solution.
