Holiday Crash

[Hairytank]

Well... I arrived back from my 10 day holiday at 12:50 Am lastnight and have discovered I have lost about 80% of my colonies...and the others are attempting to follow suit..
The house was hot humid and stank...just what you want to return to..

Parameters that I checked before water change (wanted to change water more than check parameters...)

PH: 8.3
dkh: 6 (low,but not tooo low)
Ca: 380 (low, but tooo low)
Po4: <0.25 but I am thinking this is more of test issue and actual amount is higher as there was a minor algae bloom and with all the dead coral, I would imagine it should be higher.

Lost:
large octospawn, 4 monti caps (1 purple, 2 orange, 1 green), tri-colour, 2 acropora, 2 monti superman and pokerstar (softball), 3 birdsnest (2 pink, 1 brown), 2 large misc corals, numerous frags.

Wounded but not out...completely ("I think I see a polyp.."):
large brain, candy cane, milipora, 1 large orange digi, 1 large green digi, 1 large purple digi, acan, 4 shriveled green hairy mushrooms..

The fish are all alive and looking healthy so the fishsitter did a good job...I guess I should have had a coralsitter...

Boy the tank is looking like the bad old days....
The smell is getting better in the house though....

My wife is starting to question the whole fishtank thing..