apex salinity question/temp compensation

[t blackwell]

my apex shows salt at 29.8 . I use the milwaukee instruments digital refractometer and I usually get fairly consistent results from it. It shows me at 1.025. I understand some people turn on a temperature compensation feature and if someone could tell me about that Id appreciate it explained. temp according to apex temp probe is 79.4 at the time of these measurements. I had a lefegard difital temp thermometer in there but it seems to show about 2 degrees lower consistently. I am making an assumption that the apex temp proble is likely much more accurate.

the milwaukee occasionaly gives a diff num the first time but always tests well on 1.025 solution and distilled water. its usually changes down one point I think this is temp related. I usually test it about 3 times..each sample I mean...

 

[AcanthurusRex]

The Apex temp probe is not accurate, you must calibrate it. Mine was off a degree or so prior to calibration. I finally purchased the relatively cheap BRS NIST temp probe which I call good.
The salinity probe is very sensitive to air bubbles. I hold it upside down underwater to free any air from the probe. I also calibrate in the sump since I keep the tank at 35ppt according to my manual testing equipment. Once I did this it reads well but I would never trust it for any but status only.

 

[t blackwell]

what method did you use to calibrate the apex temp probe

 

[AcanthurusRex]

Stick the NIST thermometer in the tank and change the Apex temp offset so they match.

 

[t blackwell]

thank you...I have another thermometer that i find to be quite accurate...couldnt I use that...