That gsp is crazy! Wow.

+1

Have you tried prying under it yet ?
If it were me, I'd use a jeweller's flathead screwdriver and see if I could get under the rubber mat
When I trim mine back it just peels off the LR island it's on

. Yep it's just taken off but I can see the changes weekly! Mgonna let it cover the entire back wall

Do you do it in the tank or pull the rock out? I'd have to get my snorkel and mask to do it in the tank.

I do it in the tank

Just grab the flat pointy object of choice and start digging under it
Then try to peel it off - it's like rubber/leather and will come off in sheets