<I've breed leopard geckos on and off for 15 years now and I've never had a problem with the sand substrate. I usually use sandbox sand but I've also tried the "desert sand" they sell at petsmart without any problems too. You have to be careful with reptile carpet because if it frays you lizards could ingest it.>
i too have been keeping lizards and some snakes on mostly sand for over 13years straight, then last year my brother brought home a slim but otherwise healthy baby golpher snake that died of impaction from the sand it ingested while feeding. your right that frayed reptile carpet is not a good thing for reptiles to ingest and i have heard of some people loosing pets because of it, however it is very easy to just reach in w/ a pair of scissors and cut off the loose ends.
