Brown Spots on Bubble Coral

[lee]

It had been a few weeks since I spotted brown spots on my bubble coral. The brown spots have been increasing days to days. All the water parameters seem to be constant except NO3 ranges normally

30-50ppm. The bubble will still take food but seem like not expanding as much as previous; probably 20% less. Other Invert in my tank seem normal.

Any idea what's the problem ?

[bubble_gum]

i too have prob wif my bubble coral. dun noe y wont open fully. but slowly day by day improving. maebe give it time?