White coraline?

[nitrex]

What would cause purple coraline to start turning white?
I have a couple tiny spots of purple coraline that has turned white, all on top of the rock. Is the light too strong? - 142 watts compact lighting, positioned about 5 inches from the top of the tank. The tank is only a 20 gal long. I am using two 10000K bulbs and two antic bulbs.
tests: Amm = 0, trite=0, trates<10pmm, alkalinity reads = high. My test kit doesn't provide an exact reading, only tells me low, normal, and high. Not sure what calcium is, need to buy that test kit. I do add calcium once a week though...

 

[reefaddict]

My coraline algae also turned white in my 29 gal reef tank before upgrading to 65 gal tank. The water flow is so important as well as calcium. I would definately get a calcium tester. By the way coraline algae turned back purple after a couple of months.

 

[fshhub]

dying and or regrowing will cause this, as mentioned, check your calcium(you want 350= FOR LR ONLY, 400-450 FOR REEF), LIGHTING may also play a factor in its growth
HTH