Corals randomly close!

My tank is freshly cycled and I added some new frags (zoas, mushrooms) and now my hammer, as well as the new frags, started closing up randomly during the day. I added the hammer during the cycle ( I shouldn't have done that) but it did fine I guess. It looks like it got injured or something. There are white spots on its tentacles. My zoas and the mushroom also close up but my glove polyp does not!

Water parameters:

SG: 1.024
dkH 13.1
pH 7.8
Ca 460
Mg 1300
Ammonia 0
Nitrite 0
Nitrate 0-5ppm
Phosphates 0.50

My temperature has been fluctuating lately since it's been getting really hot here in Moren Valley. It jumped from 75 to 79 within a week. I'm not sure if that could be the reason. Flow is moderate to high but the zoas, mushroom and hammer are in low - medium flow. Only the glove polyp and GSP get higher flow.

Ph and Alk seem to be off. It is def. not the salt mix though. I did a water change yesterday and tested the mixed water.

pH 8.4
dkh 11.9 - 12.1
Mg 1350
Ca 420
phosphates 0


For filtration, I use a poly-filter in a canister filter. Any ideas what could be wrong?