Second Zoo frag in 2 weeks melting?

WTH? This is my second zoo frag that has melted on me in 2 weeks!! My parameterrs are fine, no ammonia, nitrates or nitrites, no phosphate, calcium is slightly low at 380 with alk at 11dkh, I can't see any nudis, just sme somall copepod or shrimp looking things on the dying frag. all my other frags are in very close proximity and they are fine from what I can see? Please help what do I do?
oh and my salinity is 1.025 and ph at 8.3

 

I seriously wish I could help. I've had about 4 different frags of zoas and only one has made it. I have tons of LPS, SPS, and other softies that are doing fantastic. I just seem to have a hard time keeping zoas and have no clue why!

 

yeah I'm stumped lol no Zoa pox, nudis, or anything visible.. I'm beginning to thinnk it might be some type of Zoa disease.. Maybe I'll have to get some sort of a dip or medication, to dip all my frags in... blahhh more money down the drain

 

\\

lol, I'm about 3-4 months in this build and look at the $signs and go #%$! But then again, i love it! But sometimes ya just gotta bend over and take it! This hobby ain't easy or cheap!