CORAL HELP PLEASE

[Proteus]

I have a Merulina Coral that I've had for a year. It's always shown great color

The last month it's browned out and polyps have been out quite a bit. Which is strange since its never shown much polyp extension before.
Water perameters are good nothing changed. I run prodibio and carbon and rowa.
I know it a more difficult piece to care for so looking for advise

Also it's under a brand new geissmenn 250 watt 21k halide