you will be fine with the sand, all chickens need sand for grit anyway when fed treats, this way they always have access to it. I covered my pine shavings for about 4 days until I was sure they knew where their food was :)
well we couldnt find and reptile sand that didn't have added calcium or vitamins and wasn't sure if it would be harmful so we just got a 50 lb bag of play sand....wow didn't realize how much cheaper! i don't plant on having the entire brooder sand. the half under the light will be pine shavings...
well chickens use it to dust bathe. So i wanted to do half sand and half pine shavings for them :) but as for the ducks I figured itd be easier to scoop dirts sand than the pine shavings lol