pH and Salinity correlation?

[themcfreak]

Is there a direct correlation between pH and salinity? I've attached a graph, which may just be happenstance. But got me curious (my salinity seems to be ranging from 35-36 over the course of the day, even though my ATO is always on). But the peaks/valleys are very close, indicating that as pH goes up, salinity goes down?

Also attaching salinity/temp comparison, as I know they are related, but there doesn't seem to be much correlation.

Nothing is wrong, just a curiosity post

 

[Randy Holmes-Farley Verified Community Expert]

pH cycles day to night due to photosynthesis using CO2 during the day and respiration producing it 24/7.

Salinity does not swing day to night unless you set an ATO on a timer. How are you controlling salinity?

 

[themcfreak]

Tunze ATO on nearly 24/7 (turns off when feeding). That is why I was a little surprised to notice the ...anomaly of the swings. And the fact that they correlated to pH visually on the graph (which may not mean anything at all).

 

[Randy Holmes-Farley Verified Community Expert]

perhaps the temperature correction for the salinity measurement may be imperfectly implemented, and the “salinity” change is really a daily temp change?

 

[themcfreak]

That makes more sense. It is a Neptune salinity probe, which I know is pretty finicky. I check it with my refractometer and it is 35 when I check it there.