[papagimp]

Travis, that exactly the idea right there. I'll be using epoxy resin in addition to the concrete. Actual plans I'm following were found at a different site but has the same basic principles as those articles. Already tried at hobby lobby, they had nothing that I'd want to work with and charge an arm and a leg for the smallest pieces of styro. awfully proud of there stuff.

herpchat, the idea is basically to cover the entire sculpted background with a layer or two of concrete, and marine epoxy resin over that. The entire unit will be siliconed permenantly into the tank.

I'll try to get good photo's of the build but don't have a camera anymore and may not be able to get a unit on loan by the time I'm ready for this. Already have a cycled tank but then decided on this route so gotta drain the tank again. Fun fun fun.