i have been using doggie training pads & changing them 2-3x a day (nobody told me how much chicks poop). underneath is the litter & when i'm changing the pads i let them scratch around in the litter (because they love it). i just worry that they're consuming some of the litter and won't be able to digest it. the chick grit package says not to give it until they're two weeks old. so do i keep them on the covers until they're two weeks old?