Just to be clear; the Hanna Salinity Tester can be calibrated for conductivity (≈salinity) but not temperature.
The temperature range is listed in the
Hanna manual as being 0~50ºC (32 ~ 122º F) ±0.5ºC (1ºF)
This temperature resolution is pretty standard among hobby grade equipment. It's quite possible for two thermometers to differ by 1.5º F and still be within spec. The Neptune Apex probe can be calibrated (BRS made a
video about this a while ago) but most other thermometers we use in our tanks can't be calibrated. As
@Ippyroy said, consistency is more important than the absolute value.