When re-calibrating a probe that has already been in use it is extremely important to clean the probe first, even if visually it does not look dirty. Biofilms, algae and mineral deposits can form on the probe and prevent it from reading properly, if calibration is performed when the probe is not completely clean it will result in incorrect readings.

To clean the pH probe follow the below steps.

Cleaning the pH Probe

1. Decant some of the D-D Concentrated KH Manager Test Reagent into a small suitable container to a depth of 30-40mm, the glass beaker that comes with the KH Manager is ideal.
2. Stand the probe in the decanted reagent for 20-30 minutes.
3. Rince the end of the probe in some aquarium saltwater then using a soft bristled brush gently clean the bulb on the tip of the probe and around the base of the bulb where the reference junction is positioned. Any algae or biofilms will need to be removed from these areas, please see the attached images.
4. Safely dispose of the D-D Concentrated KH Manager Test Reagent used for cleaning the probe and fill the small container with aquarium saltwater to around the 30-40mm depth as before. Never use pure water or RO water as this will damage the probe.
5. Carefully stir the pH probe in the saltwater to remove any loose algae, biofilm deposits and air bubbles then leave standing for 30-40 minutes in the saltwater.
6. The probe should now be ready to calibrate.