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.