My show tank has a real problem with cyanobacteria. I get huge sheets of green cyano on the glass, some red in certain low flow areas, and I now have a new color. On my front glass I now have purple something growing. I say something because I'm hoping that it is corralline algae. Given that my showtank has circulation issues (I'm busily working on powerheads) I doubt that I have managed to grow corralline on my glass. I do get some good growth on my LR. Is there such a thing as purple cyanobacteria? What do I have on the glass?