Re: Pair Of 80 Gallon Plywood Builds
I've never used either of those other epoxies. Silicone does seem to adhere very well to the pond armor though - I would say similar adherence as to glass, at least for the functional purposes of a project like this. But, I have no proof of that. To be safer I did hit all the spots I would be applying any silicone with some 60 grit sandpaper to hopefully increase surface area for adhesion.
I haven't done any kind of objective testing of the adhesion. I will say it is very difficult to scrape any silicone off the surface of the epoxy. Also, I would hate to have to remove these panes of glass from the sides of my tanks now that they are siliconed into place. As far as the background, the egg crate will pull away from the silicone long before the silicone would pull away from the epoxy.
I built a tank with basically this same design for a friend a little over two years ago. It also has size-able pieces of wood attached to the background. It's still up and running with no problems.
Those are my experiences but definitely do your own testing before making any kind of critical structural decisions depending on silicone sticking to this particular epoxy.
Oh, also you might check on some of the forums where people are building large plywood aquariums. They use various epoxies and, I'm assuming, count on silicone for some parts of those builds as well.