I have a serious question, but first I'd like to address the elephant in the room. 1.) FACT! Octopus are extremely intelligent and amazing escape artists, and near-complete sealing of the system is the ideal way to octo-proof an aquarium. That being said, I'm looking for advice on how to octo-proof my 12 gallon Nuvo cylinder without putting a makeshift lid on it. I have seen pictures of some public aquariums that use abrasive materials around the edge to discourage animals from climbing out. My thoughts were to find a material that had relatively short "fibers/extensions" with one side extremely abrasive and the other "smooth as silk," so as not to scratch the acrylic. And because I do not want these modifications to be permanent, I was thinking of getting some plastic clips, on which I would glue said abrasive material, and clip a strip of this material all the way around the top of the cylinder, just above the water level. I would then block the overflow entrance into the back chamber with a coarse, and slightly abrasive, sponge. Please keep in mind that I intend on keeping O. Mercatoris (if that makes any difference in material selection or set-up). So,..does anyone have any input on what material(s) would be best for this project and where I can get them, and are there (if any) changes/alterations to this idea that you would advise?