Is the wall made out of actual rock? Most non toxic sealants should work I think. It depends on the material you're sealing though. I don't think rock itself shouldn't need to be sealed.
out of foam check this video out https://m.youtube.com/watch?v=T_4gCuKRCeU I made just a basking platform it came out great I used all this products now I'm going full scale,as for grout any floor grout will do grout is basically cement that will dry so nothing to worry about it.
Mirage came out of brumation on April 26. He was doing great. On May 2 he started acting funny. We just redid his tank, and he keeps going into one of his hides. He just lays there. He shows no intrest in food. HELP!