NASTY STUFF!!!! OK, there are a number of ways to get rid of it. Firstly, buy a bigger skimmer. A really, really big one. Like a good brand rated at least twice the tank volume. This rips out all the organics and makes them unable to grow. I have an ozone on my tank, I don't use it most of the time but works great in getting rid of that stuff. Siphon it out manually as well and do heaps of water changes using RO water. I'm also looking at putting some Caulerpa in my sump to make it go away.
HTH,
Tom