nitrate ~10
What does that mean? You have that reading or its less than that reading??

Your calcium could be a little higher, but, its nothing to worry about.
Leathers and other softies along with hammers, etc., give off some chemicals to repell their neighbors. It does not take much. Best bet is to run some carbon in there and see if that doesn't help. If you have all the nitrate in there, thats really too far off from 0.
What salt brand are you using? Using RO/DI???
I'd bump the specific gravity up a little with natural evaporation. Don't know if you have a calibrated hydromter or not, but, if its off, too low of a specific gravity is not beneficial to what you have.
Your lights are clean, newish?
Temperature? Using anything that could cause stray voltage?
You don't mention any fish? Some fish give off toxins too.