How to get rid of purplish deposits on glass (with picture)

[Brenden]

Thanks but I will keep my fingers crossed and hope I never have to. Thanks for the info though.

 

[pufferman]

coralline isnt that bad you know. it is actually a sign of correct calcium levels in the aquarium. Some people beg for it to grow in their tanks. As for me, i only get the purple on the rocks.