I have 6 chicks that are about 3 weeks old. They aall have there new wing feathers and are very lively. It is getting down to low 50s at night here in North Florida. I have a 250watt red heat bulb. Will that suffice for these little birds or do I need to wait a little longer? They are starting to fly the indoor brooder. My brood pen outside is 4x4x8 and I have a lamp for it for the bulb. Thanks in advance.