Chalice help needed!

[onelow64]

I've had this wonderful chalice in my tank for quite a while. However last night something happened to one side of it! Any help would be greatly appreciated!

Before last night

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After last night [emoji27]

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[ExpensiveHobby]

thats odd given I see no stinging corals next to it.
Every time I've lost a chalice its been because of an ALK swing. Maybe do a water change, dipping in iodine may help stop the spread as well. If that is a hollywood stunner as it appears they are very resilient and should bounce back

 

[Sir JRAD]

Check your Alk bud