rinse bulb in cool water between buffer solutions ,,,,,,change this rinsing water very frequently OR under a cold/cool
running tap,and YES you must soak bulb in clean water when not in use
these instruments usually have a built in temperature compensator so give this time to adjust
please read the instructions again as most of us miss something vital and like the old RAM and the young RAM on top of
the hill discussing the EWES in the paddock below,,,be patient ,,,,,,,,[ with pH metres of course]
many regards and good luck ,,,BRIAN