I have had a bubble tip for 2 yrs and he has split 14 times, i have sold 7 of them and still have a cluster of 7 that my maroons play in. I have always used a razor blade for anything on the glass, and have not had any bad effects.
here is a pic of my cluster, now if anyone has any idea on how to get them off of rock that would be awsome. I usually just use a powerhead but you never know which way they are going to move. Plus funny thing, i can put a powerhead on an anenome and it will stay for hours, the moment i turn my head and do something else, it will move like 8 inches in the wrong direction. then have to start over.