You most likely have briopsis not GHA. Mine cleaned an entire jungle in 3 weeks.So your telling me that just by placing tuxedo urchins in GHA forest you are forcing them to eat it. Thats like saying if you place someone who is anerxic in a room full of marshmallows you will force them to eat there way out. Pure nonsense!
I have 6 tuxedo urchins in my 200 gal. All of them where placed directly on GHA. Within 2 days all of them where climbing the glass, and never touched the GHA.