Green star polyps help

[Jabba]

I have bought six gsp over the last three years and they all die within a few weeks. Everyone says they are the easiest to maintain, they spread fast and are hard to get rid of. Mine all die. Can someone give me some advice or reasons why.

 

[fishski13]

How old is your tank and what are your parameters?

 

[Jabba]

How old is your tank and what are your parameters?

My tank is 3 years old. I have fish, leathers, anemone, mushrooms, toadstools,, and about six other corals and all are good. I only have issues with gsp