I have Mandarins hatching today, and I set up a small fish tank as a brooder. My question is, how do you keep your brooder warm at night. I currently have one ceramic heat emitter and one light bulb that is keeping the heat at little over 90 degrees. My problem is at night. When I turn off the light it gets way too cold. Is it ok to leave the light on 24 hrs a day or do they need a light cycle?