I've got 18, almost 3 week old chicks out in the coop. They've got a 250w heat lamp out with them and are doing great. My question is, is changing the heat bulb once per week good enough? I am scared to DEATH that the thing is going to go out during the night and my babies will freeze. It got down to 36 (yes---36 in September in Texas ) last night and I got up 3x during the night to check that stupid heat light. Once a week for a new bulb good? I keep 2 extras as backup all the time.