That pH is ok. I don't like using tap for seedlings just starting off but that's me. Especially hard water, which is what you have. Do you have a Reverse osmosis system? Or any filter system?
I would try that first. It looks like the plant is burned, but I can't be certain. I don't know how that soil mix performs.
For starting seeds I like to use promix, just peat, perlite, dolomite + mycos. Nice and basic to start em.