Even if they don't look like they need it, be sure to clean your brooders at least once a week! I have some bantam chicks in a big rubbermaid tote. There are probably 12 chicks in there, so plenty of room. They were still on paper, simply because it wasn't dirty, and I hadn't removed it. They are now about 2 weeks old. The other day I woke up to find one of my japanese chicks laying dead in the brooder, and that same afternoon found another one. Yesterday I found one of my silkie chicks laying dead in there, and all of them had appeared fine before I found them. So I decided to overhaul the brooder, and when I lifted the waterer there was a ton of MOLD underneath it!! I hadn't noticed it before because the waterer was on top of the paper, the mold was underneath. I haven't lost any chicks since I dumped the whole brooder, so I assume the mold was the cause of their deaths So please, please, please, clean your brooder, even if you don't think it needs it!