Hi all, I want to take my chicks outside to better ventilation when they are a week old. It's hot here and doesn't drop below 90 at night. Anyway, would a rectangular or square brooder be best? How tall should it be? I'll be caging in all sides, with scrap wood on the ends to help with drafts. It's 6" of space per chick, right? Will this apply when they are in that transition period before going to the coop? They are 4 days now. So, if that's the case, I would need 10 square feet or would that be 10 linear feet (I have 20 chicks)?