I used one. I think the heat output is about the same. I set up my incubator with the black light (25W) and ran it for about 3 days to stabilize temps before I added eggs. Had a good hatch with it. I have now switched to another heat source but not because I was unhappy with the light itself - just the amount of room it took up. I had to put a screen around it so that newly hatched chicks didn't run into it and burn themselves, and that also took away space.