Mine has been for a while now, and its a complicated answer. Yes, it can. But, it might be something else. Temperature fluctuations, low mag/alk
, astrina starfish (god i hate them), ultra low phosphate.... Try getting your water checked, or if you have and you know you don't have any issues then maybe its just one of those things. Did you get new lights? Coraline can bleach (which is why it turns white). When I upgraded my lights from Compact Florescent and 2 HO
t5 to the 4 HO
t5 most of my dark purple coraline died. Now i have some light purple, but it doesn't look nearly as nice.