Thanks Bradley, the true colour I see is green foot with purple/pink head/polyps. Earlier today it was facing the back of the tank now its facing the front, I'm tempted to lower it in the tank to see if less light makes it happier.
I contacted the previous owner, the only differences in his tank parameters and mine is my alk is 8 his was 10, he has high nitrates mine are 0 but I have phosphates of .10 his were 0.