Great pics and review thanks
Your tangs sure have taken to it quickly.
I found mine stays pretty intact, if removing it you do get break off but the other fish soon smell the goodies and come swimming over to clean up. I would be inclined to leave it in place until devoured (two days max) and reduced/stop your other feeding.
I also found it a good way to do a critter count they all fight for real estate under the block for any escpaing particle