Most pests are species specific. Flat worms only affect acropora. They won't eat birdnests, stylos, pocilloporas etc. I would throw pest idea out the window now if those are affected/sick. The worst problems with SPS I have seen are usually traced back to alkalinity fluctuation. The problem is stuff doesn't start showing symptoms until weeks after the accident. So it's very difficult to pinpoint SPS problem causers after they show symptoms. My LPS never seems to care about alk fluctuation