If you glue you can use urchins is my point. You are afraid of them and battling algae and despite g to chemical treatments when a little glue and some urchins would probably solve your issue.
Your tank tho
Get corals attached to smallish chunks of rubble. Glue rubble to rock. Easy enough to pry off if you want.
Not worth losing corals that come loose or avoiding herbivores that you kinda need imo