thanks I want to clean it for that reason. I have seen pictures of tanks with a really pretty pink purple algae on the back of the tank. how do you get that stuff to grow? Is it something that comes in time or only in a reef tank?
That purple and pink algae is coralline algae. It will come in time but you need to provide it calcium and your parameters in check and also some decent light( I've had it grow under PC but it really took off with my T-5's). It will form on glass and plastic parts first then to your rocks. It sure does look good covering the back glass. Mine was that way till I moved a couple of months ago and it all bleached out and went away. now I am having to start over.
I have a pc and while my tank is only 6 weeks old, all my rock is getting the color back and I have alot of new coraline growth. However, I have none on my glass.