rtn?

[props]

yesterday i watched my acro die about 3.5"tall =o(
@ 4pm notice some mucus coming out from the polyps
@ 5pm the tips looked like its being blech turning from flourescent green to white
@ 6pm more mucus coming out 'bout 35% from top tip down had turned pure white
@ 7pm the whole thing is white as a sand, green flourescent tissue's all gone.. did see some red bugs on it may 2 or 3
around midnight some green slime started growing on the tips

this morning saw my monti cap experiencing the same thing so fragged the area where the tissues are coming off when i got home early this evening ev'rything in the tank looks normal same with the cap

i've had the acropora now for 3 weeks or more
and the monti cap for a couple of weeks

tank parameters are the ff:
ph-8.2
salinity-1.023 (did 5gallon wc over the weekend as well water was 1.026)
alk-8-9dkh
nitrate-5ppm
ammonia-0
nitrite-0
phosphate-0
silicate-0
temp- ranges from 72-77 degress fareignheight
ca-460ppm (overdosing maybe?)

i did add some tank raised acros i picked up from a local supplier last weekend and all of them are doing really well

ne clue what happened guys?
=o(