Which would you believe?

[Navarchus]

You should lower your salinity to 1.024-1.026. Do it very slowly.
What brand of salt mix you use? If you lower your salinity the ca level will drop accordingly.
I recommend you check these parameters on weekly base:
Salinity, ca, alk, mg, po4, no3. Keep it on excel chart so you can identify if your system develop some tendency to go to the wrong direction.