Does tank Salinity change during the day as temperature fluctuates?

[Frogspon]

My hanna checker measures the salinity differently depending on the temperature.

When it runs at 79 degrees, it says the Salinity is 1.024, but when the water comes to room temp it reads at 1.028.

When I check the Salinity with a refractometer, it says 1.027.

Is the salinity in the tank really 1.024, or 1.028?

 

[T-J]

What do you mean "when the water comes to room temp"? Your tank temperature shouldn't fluctuate more than a degree throughout the day/night.
The refractometer should be ATC, so you should get the same reading as the Hanna, as long as it's at the same temperature. Assuming both are calibrated correctly (using 35ppm solution, not RODI).

 

[T-J]

Also, you are measuring in specific gravity when you say 1.024. Salinity is in ppm.
Most people keep their tank at a specific gravity of 1.026, which is a salinity of 35ppm.

 

[Neros503]

colder water is more dense so that will make the salinity higher, and warmer water is less dense so the salinity will be lower. so yes, salinity can change if the temperature changes, but your temp shouldn't fluctuate that much.