Yeah, I hate coralline. I go away from my tank for months at a time, leaving at home having the family do nothing but cleaning the skimmer and adding topoff water. When I get home, the coralline on the front glass turns a 48"x24" viewing pane into a 24x18" viewing pane. It's ridiculous.
I always end up just going in with a razor blade and scraping it off. It's the easiest way if you don't have an acrylic tank. I couldn't imagine dealing with coralline in an acrylic tank since you can't use a razor blade. I once tried using one of those acrylic-safe scrapers, and it was just a joke.