Giant Mexican Turbo Snails are the only ones that seem to work best. Or a siphon tube during a water change. Probably both, to reduce the volume so they can eliminate what remains.
Had it take over my fuge before and had to tear down the fuge. Never got in the display or the tangs ate it out of the display but I hate the stuff with a passion. Spreads incredibly fast.
Is that red slime? You can take a pic and a sample to your lfs store and the ycan tell you. But it looks like red slime..or cyano algea...the bad kind...but i think there is stuff you can put in to make it go away.