Birds nest problem

[kuatto]

My new birds nest(tan colored)has one of the small arms starting to bleach and shrink.I have it under 250w mh with actinic near the surface with moderate flow,all levels seem fine.The rest of the nest is looking real healthy,just the one tip,so should I cut that part off to save from spreading or just leave it?The other corals such as the gsp,hammer,candycane,green tree leather,shrooms,and several diff colored zoos are doing real well(seeing new growth daily)

Jim