What happened to my Green Chromis?

[Jim Barry]

I just lost another chromis ...... that is 3 in 3 hours

and my sailfin tang is hiding up beside my powerhead.

water parameters are

ph....8.35
sg.... 1.025
alk 13
calcium 450
temp 80
ammonia 0
nitrites 0
nitrates 0

I am running carbon and did a major water change last week.
I have a grounding probe and am running .026v in the water


I am running out of ideas