Not cords... reflection. I forgot to turn off the lights and those are my curtains you see reflecting off the acrylic. The back is painted black. In person I think the faux rock wall makes the tank look deeper, which was the goal. If I had covered the whole back wall it really would have made it look shallower, and the tank is already pretty narrow.
Keith, I'm thinking of converting to a semi-reef. Not FOWLR, but closer to it. I need something that takes up less time tinkering; you can almost hear my tank sucking up the alk and ca (fewer stony corals), and if I could not have to pluck caulerpa all the time, that woud be sweet. Problem is the caulerpa is on those branches with all the zoas.
Also, I need to get my subordinate male assessor out of there. He keeps challenging the top male and it's going to get him killed. Last time I tried to catch him, I drained the tank to the sand and STILL didn't find him.