I used a 75 watt reptile bulb (ceramic heat emitter) for 2 batches of chicks. I put it in a clamp light fixture (for a heat lamp) and it had to be pretty low to keep temp about 90, such as 5 or 6 inches above the chicks at first. I raised it little by little as they grew and needed less heat. But the incandescent bulbs work too. I found that the incandescent bulbs did keep it a little warmer.