I use cardboard boxes from day one, toss them when they become soiled. i be with bermuda hay, just because that is what I feed my horse and it is right there handy all the time. It dries the droppings out and if I am busy and it looks poopy in there I just sprinkly a light layer on top and it doesn't pack down and hold moilsture. The brooders stay almost odorless. It is cheap, handy, and they don't eat it but they do like to play around with it and carry little stems around. Keeps them entertained so they don't peck each other, even if they get crowded for a bit. When they feather in some, I start putting them outside during the day when the weather is nice, with no bulb, in a half inch hardware cloth brooder cage I made. I have found that smaller silkie chicks cage get their feet caught in that stuff because of the extra toes in back, so I don't put them in it until their feet grow big enough to be safe in it.