Went back and reread the thread.
I don't think it's the salt but related to high alk and low nutrients.
I missed the 10 alk.
I have ran my alk at 7-7.5 for years with lower nutrients. Po4<.1 no3<5.
Higher alk levels need higher nutrients.
Feed the system more or dose no3 and po4 to bring them up is what I would do.
I would also look at why your ph is that high and is it accurate?
That seems odd as most fight low ph.
My system is a 150 60×30×21 with 9 fish and currently 1 year old. I feed the fish heavier than most at around 5-6 cubes a day in volume.
My WD in the previous pic was only 9 months old from a frag when it went in.
I still believe it's bacterial driven in many systems but what causes it and where did it come from is the mystery.
It may have been on the edge and changing the salt may have been what caused it to stn.
This was my last handheld test and it matched the current icp I sent out.
Do you have a FTS?
And my current 1 year old system.