red algae turning white

[KLN]

I have been cultivating macro algea, and seeing a reduction in phosphates, down from about .25 to .1. I have a lot of red and purple stuff on the live rock that I presume is red algae, though the lfs fellow said there was some sponge on the rock. Whatever it is, some of it is turning white. Is this a good thing, reflecting a reduction in phosphates, or some other phenomenon?

[kwan]

When I set up my new tank about 2 months ago, I put lots of LR in there. They were covered with coralline algae (red and purple color) and some white patches. The white stuff slowly changed color to red and purple as my tank matures. So I can only guess the white stuff is a sign of coralline algae growth.