Cyphastrea receding overnight

[DiamondReeferr]

So I’ve had this cyphastrea in my tank for 13 months and it’s been totally fine and everything has stayed the same then I woke up this morning and half of it is dead and it’s continuing to just die off. I tried breaking it off the rock to try to dip it but it’s just totally stuck on my base rock. All parameters have been constant and no new changes other then replacing my chemipure elite and purigen last week. Any ideas? Pest maybe?

 

[davidcalgary29]

Please post your water parameters and we'll probably be able to sort it out. Obtaining readings with quality and reliable testing kits is a must. In particular, check nitrate, phosphate, and salinity.

 

[EeyoreIsMySpiritAnimal]

Any chance something is stinging it at night?
I see what look like vermatid snails; their webs can irritate coral.

 

[DiamondReeferr]

Nitrates are 1 and phosphates are almost undetectable using salifert test kits. Salinity is 1.026. It’s just rapidly dying never seen a coral die so fast out of no where. Crazy thing is that I had it for so long and it was doing great just like my other corals then out of no where it just starts receding

 

[EeyoreIsMySpiritAnimal]

Alk, Ca, Mg?

 

[DiamondReeferr]

Alk, Ca, Mg?

Alk 7
Cal 455
Mg haven’t tested it yet but should be in normal range

all params have been relatively stable no major swings

 

[MaxTremors]

Are there any other corals within 10” of it? And if so, what kind?

 

[Spare time]

The only thing I could imagine would be stinging or a nasty infection. ULNS tanks would require that coral to be fed the appropriate food at least daily so that is something to keep in mind.