HELP!!! corals melting

[litlepig11]

hi, only some of my corals are "melting" others are thriving...some are just complenty gone already....we went on vacation for a week. the sitter said our tank got up to 83, but i dont think that alone is causeing these problem. tank stats:
ALK= 3.0
PH= 8.2
nitrate 5
Trite=0
ammn=0
Phosphate=unkown
Magnesium=1350ppm
Calcium=475
Temp=78-80f
specific gravity=1.024
Lighting- i have MH w/t5 actinics on 8-10 hours a day, no other light sourse in the room, we use ro-di water the bulbs are about 7-8 months old
The tank is 100 gallon stocked w/live rock we have a sump w/skimmer and nirtate sponge
the tank is full of like a brown fuzz like hair, dosent look like alage, we feen 3 times a week and does w/iodane every other week. also a h2o change every other week 20%
brain is looking the worst, lost color and is reseceing, gorgian is great. colt also great kenna tree great, zoos not opening..elephant ear white spots, toad stool slime co

eb like, not open zenia shrivled, shroms umprella is ifiy the rest are gone.

should i move them to a foster home, what is causeing this...sorry i dont have a way to post photos any help would be great
thanks

 

[litlepig11]

bump anyone???

 

[exlfs]

As I will probably AlWAYS ask, are your water parameters where they should be? Post them if you have them. If you don't have them, GET THEM! Immediately!
However, assuming that your water parameters are appropriate, 'melting' as you described are likely the result of either temperature swings (specifically, given the corals you listed that are 'closed'), or you might have trace copper or some other heavy metal present. The main question for me regarding this is the speed with which you noticed the degradation of the coral tissue? Hours, days, weeks, moths, etc? I'd guess weeks.
Here's what you need to do (IMHO):
1. Post water quality parameters including copper and phosphate.
2. Ensure that your thermometer is working properly and you are not experiencing spikes that exceed 4 degrees per day (really should be MUCH less than this ideally!), and the temp is not really exceeding 82 degrees for any length of time.
3. Be sure when you check your water quality that you get your specific gravity tested. Frequently folks forget to calibrate theirs. This can be something that sneaks up on you and bites you in the bum! HA!
Best of luck, and I'll try to check back for your results.
God bless.....