Pro-tip: When you apply the Pond Shield and it is still wet, sprinkle some large sand particles all over it before it cures. I do this in my night boxes and it works great.I thought about using some kind of epoxy; would definitely seal the concrete. I still have a can of Pond Armor somewhere. My only concern would be making the pond too slick for my torts to get out of, so I'd have to make the entrance/exit REALLY shallow.