I have find some nice rough texture floor tile however the backing has adhesive. My idea was to take another tile and stick it to the other side making a double sided tile and use that hence eliminating the adhesive part.
From what I've read the main concern with adhesive is toxicity. I have had this setup in the house (not in tank yet) and smelled nothing, even heated it up with a hairdryer just to see and still nothing smells. Also can it really be that much worse than the glue used to hold his tank together?
I don't know that toxicity is a concern. It's just tougher to clean the tank if the tiles are stuck down. It's good to be able to lift them out to bake them and clean the tank along the sides and underneath. Double siding the tiles might work. Probably worth a shot given the relatively low cost of ceramic tiles. If it doesn't work the way you expect, you can try a different option. My tiles came in a 6 pack box and I had them trimmed down to size at the store.