I'm no newbie, just always been leery of anything not slate, that's porous. Makes me nervous. Also, if anyone has it in their tanks, would love to see how it's set up.
Sandstone doesn't lend well to serving as pavers. Fill a bucket with water (test the pH) and then drop some pavers in. Monitor the pH for a week. If the pH skyrockets, they aren't sandstone and you shouldn't use them in your tank.