Yea.. Definately use slate tiles or paper towels. Now I have hermit crab sand UNDER my tiles to get rid of air pockets and distribute heat evenly, but my leo can't get to it since it's.. ya know.. under the slate...
Personally I would NEVER use any type of sand. I would never risk the health of any of my leos like that.
I use either paper towels, reptile carpet or tiles.