I tried a little wading pool for my 6 week-old dual purpose chicks. I filled a wide, long, shallow tub with 2" of water and threw a handful of fresh clover, grass, and their favorite garden greens in the middle. I didn't know chicks liked to play in the water so much... they not only figured out that they could cool themselves by wading in it (and drinking it too), but they also jumped in and started squawking at me every time I approached the run, hoping for more treats. I added a cup of ice to it every couple hours to cool it, but not enough to make it shockingly cold. Since they like to drink from it I emptied and refilled it often, and they seemed to enjoy a little ice in their regular waterer too. They loved their chilled watermelon but I try to only give it once per heat spell, I know I felt crappy as a kid after drinking tons of cold sugary drinks instead of water and then going out in the heat.