I don’t know what to tell you. Aptaisia is one of those you kind of have to keep and eye on and live it to some extent. It’s a nuisance but it’s not actively killing anything. Yes, when they’re out of control, it’s a horrid sight but it can’t kill your corals overnight.
You can take out the rock and scrub them off but I’m not sure that will eliminate the issue forever. And that’s a lot of work on an existing mature tank like yours. And so what you have eliminate them. For how long? A week, a month, a year? Every tank will have aptaisia. It’s just a matter of time and all you can do is to have enough natural predator to control it.
I think what you have as natural predator will work but it will take time. I like to use aptaisia X or Joe’s Juice on the larger aptaisia and always have peppermint shrimps or other natural predator around to keep them in check.
FWIW, when I had my old tank with angelfish, there was not one aptaisia in the tank where The angelfish are even though the overflow box was an aptaisia farm. I see it as an extra filtration stage.
