Dumb question about temperature

[PirateLove]

Does temp affect salinity? I know this is very stupid but if I mix up a batch of saltwater at 35ppm at 60 degrees, then I throw a heater in it to get it to 80 degrees it will stay the same salinity right? For some reason I have hear that something is important to check at tank temperature of it will throw off the results.

Thanks! :rollface:

 

[wij]

Evaporation would effect salinity .

 

[CarrieB]

I think the question would be is all the salt properly dissolved?

 

[Member No. 1]

Yes it can.
Read this for more indepth info.

Particularly this section: Temperature and Refractive Index: ATC

http://reefkeeping.com/issues/2006-12/rhf/

 

[WaReefer458]

On the side of the container for your salt it should say what the salinity is depending on the temp.

 

[AquaAdam]

Interesting article. I've gotta see if my refractometer is calibrated properly

 

[username in use]

Does temp affect salinity?

The right question is "Does temperature effect the results of my chosen method of measuring the salinity?"

And the answer is - Yes.

The article linked above is a good one.

 

[Dmorty217]

Interesting article. I've gotta see if my refractometer is calibrated properly

You should do this often to prevent the refractometer from getting out of whack, thus causing salinity to rise (more than likely) usually doesn't end up causing lower salinity in tanks

 

[morpheas]

The right question is "Does temperature effect the results of my chosen method of measuring the salinity?"

And the answer is - Yes.

The article linked above is a good one.

Temperature affects salinity period. It doesn't depend on the method of measurement. Salinity really means salt content in solution (i.e. specific gravity). The specific gravity of the solution changes with temperature. This means that if you were to pump 1000 cc's of 1.025 g/cc saltwater at 50 °F from a bucket and measure it's weight it would be 1025 grams. Now if, with no evaporation, you brought the temperature of the bucket up to 80 °F and pumped 1000 cc's of liquid and took it's weight it might be 1024 grams (coming up with a number, haven't done the calculation). That is because the liquid will expand with heat (much more so than the salt in solution in it) so the solution salt in the mix will "dilute".

What does this practically mean though? You want your salinity to be 1.024-1.026 g/cc at the temperature your tank is, circa 78 °F. So if you mix your salt at lower temperature you will have a slight difference in salinity (lower) than what you measured. You might not be able to detect the difference with a hobby grade refractometer because the temperature (and thus salinity/gravity) delta is not big enough (say you mix at 65 and you measure again at 75).

All in all, the gist is, be consistent at how you measure you salinity on your mix, your tank etc. That contributes to the reason most reefers throw in their mixing stations a heater set to the tank temperature.