Kh director with problem

[max@star.srl]

good morning everyone, I have a problem with my kh director, after three months of perfect functioning, he began to measure a kh between 12 and 13, verified with traditional tests the real kh is 8, so I performed probe calibration, emptying cell, but still not working properly, at this point I set a 25% reduction and began to release more precise data. but it doesn't seem normal to me. how can I do ?
Tanks
Max

[Vinny]

Check the pump calibration.
If using the in-line sample water filter, make sure it is not dirty or getting clogged.
Make sure the vent tube is not submersed in water.

More troubleshooting tips can be found here in the knowledge base:
https://www.aquariumcomputer.com/knowledge-base/achieving-alkalinity-stability-with-the-kh-director/

If you continue to have issues, please open a support ticket so we can provide further assistance.

[AdrianF]

Take kh Direktor apart. Look inside because it can be damaged reagenz tube

[Vinny]

Take kh Direktor apart. Look inside because it can be damaged reagenz tube

Please do not open the KH Director unless instructed to do so by one of our support staff.
If there is a security sticker on the side of your device, opening without approval will void your warranty.