:wavey: Welcome to the forums!!!
Like Daisy said, sand can irritate scales...It can also get into noses and mouths..and just about everywhere else :eek1: (think about all the places you find sand when you get home from the beach...) A wood substrate is a better choice (aspen, birch, etc.) Stay away from aromatic wood like pine or cedar..the oils can be toxic.
:cheers: