I have a in-ground 20,000 gallon pool with Jandy equipment including the PLC 1400 and Aqualink. Yesterday I measured the water salinity at 3500 ppm but my 1-touch displayed 1900 ppm and a message to add salt. The Front Board display showed Salinity of 1900 ppm and the " add salt " LED was lit and it showed error code 144. Since the Front Board shows the wrong Salinity value, my 10-year old Trisensor could be bad. But if this is the correct diagnosis, why did the Front Board not show an error message of 172 or 181 ? I appreciate the help.