What size and what pull are the magnets in my Submersive. I was looking at putting some blank panels on the wall and ones used on the sub and Cat 12's look like they would do the job.
The heavy duty velcro that you can purchase from HD will hold a small tank. Just make sure that in addition to the adhesive, you also staple it to both surfaces if possible. The velcro won't come apart but the glue may come off the surface without staples.