Coraline algae

[boardryder]

I have a good amount of coraline algae growing in my tank, but have a few questions about it. Is there a difference between the purple, red, and dark red? Why might it seem to grow more on certain rocks than others? My parameters all measure correctly and I have put my po4 problem in check but occasionally some spots of it turn white(though it will eventually come back?

 

[Deanos]

Each species (colors) of coraline has its own preferred parameters (i.e. lighting, water flow, calcium/alkalinity/magnesium levels)