cyano

Ok so I have been through a lot with my current tank and set up but I am starting to lose some very hardy corals and as well there are some things and corals I would like to rid my tank of (blue clove polyps, xenia.) My rock I bought "live" but it is not very porous and I think may be leaching some bad into my water as well. So I am thinking about "starting over" and wanted to get some input.

First off if i do this my equipment and tank would remain the same but ...

Hey guys can't help but the write real quick and ask what is everyone biggest mistake so far in this hobby? at this point as I watch yet another blue clove polyp spawning I wish I had never put that coral in my tank, they are worse than xenia once they start spawning and there are so many of them I think they are the reason I am having issues growing sps....