Just use kalk powder in a very small amount of hot water and a syringe from a children's cold medicine and start shooting away. Do half one night and the other half the next, if you have a lot. I used to have over a hundred and it took me a good four times of doing this. Eventually they may...
If you have plenty of live rock so they could eat coraline you shoudn't have a problem. They will stay off the glass and stay on the rocks. I have a pencil urchin for like 3 years and a tuxedo for 2.
I have one in my 90 and I have a crocea and a gigas and doesn't bother them. He has taken bites out of my leather toadstool and xenia and aiptaisia for that matter. But not enough where things don't heal. I think he gives everything a try, but I've had him in there for over a year and a half.
When I get pieces of Colt whether they fall off or I cut, I just find a decent sized rock and push it into the rubble with rock on top of the pieces that is cut. In a few days it will attach itself.
Try a bi-color angel, I have had two of them and both times they have gotten rid of the aiptasia in my tanks. I had a 55 with quite a few, then I moved into a 90. I lost my first one expermenting with vinegar and kalkwasser and turned off my carbon in my tank. In my 90 they were getting out...
