berghia are good but they strictly eat aptaisia, and they are very blind and slow eaters, what usually happens is that they do a good job when the aptasia is plentiful but as it starts to thin out they literally starve to death while seeking out another aptasia to feed on. in a small tank they do well but in anything over 20 gallons they will work in a very limited capacity. that and they do not ship well at all.

You can also try a copperbanded butterfly fish, I had one of those and he wiped the tank out in literally 2 weeks. but your tanks biolode is almost capped I would try kalkawasser or an injectable solution. you can get joes juice too which is literally kalkawasser paste.