I am getting 55 chicks in a couple of weeks. I have never brooded this many at one time before, and I am wondering if I need two lamps. I have two, but I have never needed to use them both for the same batch before. Our temps have been around 40 at nights and between 60 and 80 in the daytime, but I am sure it will probably freeze before they get here. They will be in a wooden enclosed chicken coop, I think it is insulated, with a couple of vents. I have also never had fall chicks before. How old do they need to be before I can shut the heat lamp off at night? I normally do it when they are feathered and it is warm, but I am afraid that it will have to be on most of the winter now. Our normal lows are between 10 and 30 degrees, but it can get down to -20. Any ideas?