I am thinking about putting a wall of live rock behind the red line in my tank. The space that I would use is about 6 inches by 30 inches. I want to place the rock all of the way against the back wall though. Is that okay to do? I am trying to keep the full front area open to enable me to have a larger swimming area for my fishies... I was just uncertain as to the rules of live rock and placing them against the wall.