For the first couple of weeks, I brood my chicks in a long aquarium. I put the light at one end so that if they get too warm, they can go to the other end. This way, they don't overheat. I keep my water at the cool end to 1- encourage them to explore the length of the tank and 2- minimize evaporation. I start with a 70 watt household bulb. As I notice the chicks spending more time at the cool end of the tank, I downgrade to a 40 watt bulb. So, my chicks are 4-5 days old. They don't clump up when they're awake, but tend to cuddle up to go to sleep. I'll notice the occasional chick panting, like it's hot, except that they're right in the hottest part of the tank. Then it will stop panting, and cuddle up with everyone else and go back to sleep. Why would they pant if they're not hot? And if they're hot, why are they insisting on staying at the warm end of the tank?