The change in your salinity reading if very likely due to the temp of the water as well as
FW run off. The surf is not a good place to check levels.
SG is directly affected by temp. If you have walked in the surf I am sure you have felt the cold and warm spots. This on top of run off and inlets and pollution and well you know what I mean.
As far as how salinity affects
PH..It does not. From my post.
Salt mixes are designed to be mixed at around 1.025 so by lowering the salinity you are also lowering everything else,
CA etc.
Since we do not make
SW with pure "salt",
SG does affect
PH. Since a reduced salinity equals a reduced everything else "
SG". You can make water with salinity of 1.018 buffer
PH as well as 1.025
SW after you dose
CA , buffer, etc. What you are really doing by dosing is raising the
SG since these additives are denser than water.
Back to the original question.
is Ph more table at higher
sg?
Yes higher
SG does directly help maintain
PH if you are using salt mix.
One thing to remember is a hydrometer actually checks the
SG of water but gives you a salinity reading. It is just assuming you mixed oceanic or whatever brand you use and took a reading of the water. It does not know what is making the water denser (higher
SG) it is calibrated to the idea you are using salt mix.