Best saltwater temp reader???

[Richard savage]

I just purchased a Milwaukee MA887 Digital Refractometer that reads salinity and temp, the only problem was how far off my temp was between the two, Does anyone know how accurate they are ?

 

[Fudsey]

I have 3 thermometers used for my tank and they are all different but not by that much.

My Finnex controller is set at 79, the thermometer in my tanks reads 77 and the other one I have in my sump reads 75..... Which one is correct? I have no idea. I have also used 2 different insta-read kitchen thermometers and they read differently too.....

 

[jda]

Glass thermometer is still the most accurate.

 

[Sod Buster]

I get mine out of the cupboard and let it sit out for an hour before testing. It takes a bit for the stainless sample ring to warm up. You are just putting 15 drops of water into it. Let the ring warm up to 75, then test. It has temp autocorrect built in though.

 

[Sleepydoc]

The sample size for the Milwaukee refractometer is less than 1 ml (100 µl, actually) By the time the refractometer takes a reading the water sample will have changed temperature. It may be accurate but still not the same temperature as the tank. On top of that the temperature accuracy is ± 0.5º F. If you have two digital thermometers with the same accuracy, they can easily read 1º apart and be within spec. The refractometer primarily needs the temperature to allow it to compensate to give an accurate SG reading.

A good glass thermometer is probably the most accurate, but like with many things in reefing, absolute accuracy isn’t critical; it’s the consistency.

 

[805nano]

You can calibrate thermometers with ice water, fill a glass with ice and top off with water, stir and wait 5 minutes then the thermometer should read 32F and just note how many degrees its off by, not sure if it would work with the milwaukee though

 

[Richard savage]

Is there a good or preferred brand any one uses for an accurate glass thermometer ?