Hi NyKeri,
Please don't. Shells and sand (all types) are very bad for dragons. Best bet is tile or reptile carpet or a combination, since it seems like from reading posts that a hard surface might be rough on their joints if there's not a little give to it. What I've done for mine is 2 layers of a pet stain-resistant carpet from Home Depot over wood, though carpet over tile would achieve the same thing. There is actually a thing called reptile carpet that's supposed to be easy to set up & clean, but I went with the other kind of carpet (after finding one that wouldn't catch his nails) because his viv is about 4'x4' and reptile carpet can get expensive to cover that much real estate. The bottom layer is fixed to the 'floor' and the top layer is removable so that I can keep it clean, which is very important.