Any hard rock about this size will do:Can you just offer them clean sandbox type sand or do you need to buy parakeet type grit for chicks?
That's what I did with the DE I bought. Not sure if it actually killed the ants, but made them relocate at the very least, so good enough for me.But reading lots of entries here on BYC, I am now convinced that DE is a terrible idea, hurting the lungs of chickens and chicken keepers alike. So, Keep that bag in case of ant infestation, maybe?