Oh, the perimeter around the rock is very important for me. I need to have that magnet access everywhere around the viewing area. I guess I got an OCD when it comes to cleaning the glass<lol>. That's part of the reason I had to restructure everything too. The brain coral kept slipping from it's spot, and when I went to clean the glass, I kept bumping it. Eventually, all the structures around the brain fell completely over. Moreover, those structure are more or less connected to different rock formations around the aquarium, and those fell over too. To answer your question, Lyn, it took up 'til just recently to get that perimeter nice and secure (thank you Mighty Putty looking aquarium putty); it's been an ongoing process. But to fix that whole brain coral bumping/restructuring fiasco, took me an entire night - didn't sleep a wink 'til 10am. My New Year's resolution: Keep the "Reefkeeper's Arm" coral out of the aquarium.