Well it certainly dies back in my MH tank. Goes from purple to pink and then whitish pink. For some reason dosing kalk seems to start bringing it back.No light alone. several, actually many many observations of others tanks with NSW+ level alk and mag levels, report loss of coralline with higher pars. I would have questioned those parameters and dosing method but would have been off topic. If you google many Par charts and look at higher Par tanks, you'll see a correlation. The common Purple seems to die off unless in shadows, powerheads, sumps back walls etc while reds and others remain.
This seems to happen above the 350 400 par mark.
Mainly an ongoing question I have.