I'd just let the coriline algea grow and it will hide the overflow a bit slow bit it will be a natural look once it has grown in. I've been scraping coriline off the back wall for about a month now It has been growing there better than anywhere else since I'v been dosing with purple up. My rocks have been growing coriline prity good but the new sea urchin eats a bit of it along with the algea roots it's taking out of the tank. Urchins very good algea eaters.

Bill