day gecko substrate...??

[wonder_chunky]

hey,

i want to put a substrate in the bottom of my day geckos cage...but when they eat the (literally) attack the crickets by diving on them and eating them....so they'd probably get some of the substrate in their mouths every once in a while....what kind of substrate can i use that wont harm them if it is swallowed? is that calci-sand stuff any good??

thanks,