Hi, im doing a new aquascape in my TMC Signature 450. The Aquarium is 450mmx450mmx450mm. I'm thinking of adding an exo terra rock background and just wondering if anyone has had any experience with them in aquariums. The backgrounds are made from polystyrene and are normally used in terrariums. My first thought was that it would float but the background I have bought is exactly 45x45cm. The same dimensions of my tank. I also have an RMS Bracket for my Radions which will keep it clamped down and my real reef rock will hold the bottom from pulling away. I want to glue real reef shelf rock onto the background to create a shelf look to attach corals. The only worry is what effect the background would have on fish and corals. The background cannot be toxic as it is used in terrariums submersed. Any ideas would be appreciated. Bellow is the background.