Measure salinity in ppt or s.g. ?

[Taxus812]

Hi
I have been measuring my salinity using specific gravity only because it was the scale I first read on the hydrometer. Not exactly science.

Most meters can use either ppt it s.g.
Does one scale have advantages over the other ? It seems like many calculators and such use ppt?

I tried to look up info and I know S.G. is effected by temps but my refractometer compensates (is suspect most do).

 

[Reef-junky]

Not sure but my guess is ppt is more accurate.

 

[robocop1906]

If you are not using a controller to monitor the SG is fine. Even with a controller I periodically test the SG to ensure the ppt is accurate due to the nature of ppt probes. As long as you keep up with testing and ensure it's stable you should be fine.

 

[WVNed]

The best scale is the one that is most meaningful to you.

 

[Taxus812]

I decided I am going to convert to ppt. A hydrometer and refractometer it wouldn’t matter much. My Hanna is digital and can display a reading in S.G. to three decimals (resolution) but it can can display ppt to one.

I just did some conversions and if I had a salinity of 34.6 ppt my meter would read 1.026 s.g AND if I had a salinity of 35.8 I would still get a reading of 1.026 so using ppt will give me a bit more resolution.

 

[Reef-junky]

Not sure how you would do it with SG but with ppt you could mathematically figure out how to mix your salt not that it matters.