Temp v Salt

[pREEFERED]

Why does the salinity in my tank increase when the temperature of the water increases?

I understand that as the temperature rises, water evaporates faster, but since I have an ATO that replenishes the evaporated water, shouldn’t the salinity stay level rather than reflecting the rise in temperature?

I have a reefer 170 so perhaps its due to the smaller water volume and the salinity probe is really sensitive to the fluctuation, but I wanted to see if there is something else going on which I am not thinking of...

https://uploads.tapatalk-cdn.com/20180628/62fdf325e7e55c0f31bb21f7595d798e.png


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[mcgyvr]

Specific gravity is changing because the density of the water is changing in relation to the temperature..

http://reefkeeping.com/issues/2004-07/rhf/index.php

[pREEFERED]

much appreciated!


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[bertoni]

That range is very high for a tank with a reasonable accurate ATO system. How often is the system running? Does the Apex have ATC (automatic temperature compensation)? If so, is it turned on?

I agree that a hydrometer will show a range of temperatures, but a probe with ATC should be more stable, I would hope. My meter was.

[mcgyvr]

Does the Apex have ATC (automatic temperature compensation)? If so, is it turned on?



Sure doesn't seem like it as its tracking very closely to temperature..

[pREEFERED]

Sure doesn't seem like it as its tracking very closely to temperature..



agree that a hydrometer will show a range of temperatures, but a probe with ATC should be more stable, I would hope. My meter was.[/QUOTE]



ATO is a Tunze Osmolator 3155 so it only turns on once the water line drops below the sensor, no ATC for the Apex (though that would be pretty sweet), but I also have an AquaEuro chiller that is set to kick on when the temp rises above 81, indicated by the spikes... the chiller is also set to run for 1 min every hour to cycle the SW that sits in the chiller when it turns off to prevent the water from getting stale.


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[bertoni]

Given the temperature range and the unknown precision of the ATO, that range might be within reason, although I might try double-checking with another SG device, if that's easy to do.