calci sand can imapact geckos, a lot of the loose substrates can. I personally am too much of a worrier to risk it, I keep mine on papertowels. There are people on here however that do keep theirs on sand, if you really want to use sand feed your gecko in aseperste tank. Most impaction is due to accidental ingestion while feeding. Hope this helps.
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7 Leos
Milo(my adult male) Mongo, Raptor,and Spaz
Popeye and Boo(named after Monster's Inc. Character)sex unknown, but I am pretty sure they are females.
Pumpkin the Patternless (he's a boy too.)
1 Female Sandfire X Blood Aboriginie Red Bearded Dragon. Tequila Sunrise, Tequila for short
1 dog
Baby (Peekapoo)
2 Cats
Mr. Kitty and Shelly (my adopted senior citizen. She's 14!)
I lost my baby blizzard may he/she Rest in Peace