I also have B. skottsbergii. It is such a pain. It popped up on some live rock when I first started, and when I researched it, I was told it was unusual, a sign that my tank was thriving, and I should enjoy it. So I did, until it started growing out of control and smothering my corals. I run a phosphate reactor and do carbon dosing and it still grows. It grows a little bit slower than it used to, but it still grows. It started to turn white and die off a little bit when I first started the vsv dosing, but now I think it's resistant. I'm convinced my rocks are leaching PO4, and eventually with good husbandry it'll just starve. I recently borrowed a juvenile surgeonfish and he did a good job eating all of it, so we'll see how quickly it comes back. My advice is to get it out of your tank if you can while it is still at a manageable level. Unless you're willing to constantly prune it and keep it trimmed back, I think in time it will grow all over your tank. It's good that your phosphate remover seems to be killing some strains of it.