Based on what you've mentioned previously, I really think you need more flow. The powerheads you have are fairly small for a tank with your dimensions. Is the cyano in the sand or rocks or both?
Everyone will tell you that a 3-day lights out is all you need to do. I have done it and almost every coral I had bleached out. They cam becak but it was close on a couple. Your nem is not going to like a blackout and will likely move a lot during teh time the lights are out. My suggestion would be to increase flow and possibly replenich your CUC. Is the wrasse picking on your snails/hermits? If their constantly hiding from the wrasse, they're not doing their job.
Are you running any media?