Acropora dead over night?

I received 2 pieces of acropora and a pink birds nest. I did an iodine dip for 5 minutes and then placed all 3 pieces in my frag tank just outside of the light. (light was on them but they weren't directly under the lights) I woke up looked at the corals and the 2 acropora were completely white and as far as I can tell dead. The birds nest that was right next to them is alive and doing just fine. What should I be looking into as the cause of death? I'm slowly getting into LPS. My tank is 2 years old and LPS is growing like crazy and haven't had a coral die in over a year.



I do 30% bi-weekly water changes.

Temp: 80.5

Salinity: 1.025

PH: 8.14

Phosphates: .03

Nitrates: ~0

Nitrites: 0

Ammonia: 0

Calcium: 400