Green star polyps out of control

[Slick Fork]

Hi there,

As the title says, I've got some green star polyps that are going out of control. I thought they looked neat when I first started out, now I don't mind them but I don't particularly care for them anymore and they're taking over everything. They just recently attacked and killed a small birdsnest frag so I need some ideas on how to control this plague without nuking the entire tank. I tried boiling water but they just laughed at me

Thanks