I super glued mine to the back, both to the acrylic overflow and the glass. No issues. Snails go on it all the time as well (no worry when it was glued as the glue is cured long before they get a chance to get near it)
Id like it to cover most of the entire back if I can, one day
This was it when I glued pieces in... August/September. 2nd pic is what its like now.
