Help!!!

[jjkim]

I am taking care of my friends 72 gallon bowfront tank while he is in training in naval academy
and suddenly the flame angel and bangai cardinal disappeared i checked under the rocks, sump and no where to be found and two days after corals started to die i think about $400worth of corals died
However when i checked the water everything is fine so anyone has idea why this happened and where the fish went?
I just want to bring his other corals that survived back to life
the naval academy took his phone and can only receive hand written mails so he doesnt know about this
Also his other fish are all alive and healthy he has a six line wrasse two clown fish, blue hippo and yellow tang about 2 inches and one damsel
His tanks light is t5 quad ones and with 2 led in the sides of the t5 and one in front of the t5
Any idea why this happened?? Thanks

 

[Cailp02]

When you say you checked the water, what does that mean? Keep an eye on the water temp.

 

[thirty6]

Is the tank pre drilled? I recently found two fish in the overflow box

 

[Reefcowboy]

It could be temperature. These days have been extremely hot. I assume the tsnk is in his place, do you leave the ac on all the time or has it been off since he left?

 

[jjkim]

Oh i meamt like nitrate and all the stuff from the test kit
And yes! The water was rlly hot like maybe 83 degrees could that have been a reason why?