GSP losing colour

[mucky1957]

hi guys
I have a number of pieces of gsp..some large some small and they are dotted all over the tank A few are losing their 'geen' colour and are becoming lighter ( defo NOT bleaching ). Water parameters are spot on and everything else in the tank is fine.
Is there a chemical or even a food substance ( reef roids ? ) that I can add to the tank to bring the gsp colour back and maybe even enhance the colour of the other corals.

thanks

 

[Tahoe61]

Have you changed the lighting? And lighting type please?
Is the system a low nutrient system?

 

[mucky1957]

Have you changed the lighting? And lighting type please?
Is the system a low nutrient system?

lights are exactly the same..no change for 2 yrs. Its not a low nutrient system ( as far as I know ) Some of the gsp is a glorious vibratnt geen and some now is much lighter..

 

[Randy Holmes-Farley]

My GSP turned entirely white in low light.

If it is impacting some and not others, it doesn't seem a chemical deficiency is likely.