There were two things that got me pretty good. First was GHA. I went on deployment and when I got back the tank was full of it, took me months to get rid of most of it. There are still patches here and there, but are easily pulled out. The second and what seems like worse to me is Pocillopora. I got what I and the store was a green birds nest. WE WERE WRONG!!!! The stuff is everywhere and I am working to get rid of it. However, it seems that it may be easier to cycle some new rock and just save the corals I do want. This stuff is a nightmare.