One thing I find with peppermint shrimps is they will only hide in the crevasse and especially if you have wrasses constantly hovering, so it's best to get a few more for a bigger tank.....

Berghias work at night so you never see them, at one point my tank had over 1000 aphasia, in 3 months there was none, they take awhile to get going but once they multiply they clean house pretty good....

I have 5 peppermint shrimp (or should have 5) in there and havent seen any aptasia go away.

so maybe I just put the rocks in the sump and add more shrimp in the display and see if that helps.