At what age can you put sand into a leopard gecko's cage?

Sand is the leading cause for impaction. Once the animal ingests sand, it can build up in the digestive tracks and the animal won't be able to pass it. Once impacted, most animals will not eat or drink due to the pain and this can lead to death. Most breeders do not reccomend loose substrates for this reason.

Baby geckos of almost any specie can live comfortably on papertowel substrates. This allows them to seek out a damp/moist spot in the terrarium when shedding, as well as live feedings being able to take place within the terrarium.