Chalices receding

[Ribcribdan]

Have a established reef tank about 5 years now. I have lots of sps in the tank that do very well, but most of the time when I add a new chalice frag it looks great for a week or two and the starts to slowly recede. I have good water parameters I do not know what is wrong. I have some chalices that have been there for years but anything new does not do well. thanks for the help.

Cal 450
Nitrate 10
Kh 9- 11
Pos 0
Salinity 1025
Mag 1500
Lights ai sol blue led