The red lamps heat by infrared rays. The rays warm the chicks themselves and whatever the rays are shining on. Measuring with a thermometer underneath one is misleading since you are reading the temperature of what the infrared rays have heated the thermometer to, plus the surrounding air which really isn't affected by the infrared lamp. A white lamp puts most of its energy into heating the air around it and not much heating by the rays of light.
If you are brooding chicks in a large room, shed barn, with just a brooder ring around them , hanging an infrared lamp is the way to go, the rays shine down and warm the chicks... Hanging a white light above them may give a little bit of warmth from the white rays, but most of the energy goes into heating the air around the bulb which just raises to the ceiling.
A white light will work in a smaller container. Especially one that is partly covered or under a hover that will trap the rising heat.
Temperature control is really not all that crucial. Give them a warm area and a cooler area. They adjust themselves as necessary. If they are piled up directly under the heat source, they need more heat. If they are crowded around the sides of brooder panting and trying to escape the heat, then obviously it's too warm.
If you are brooding chicks in a large room, shed barn, with just a brooder ring around them , hanging an infrared lamp is the way to go, the rays shine down and warm the chicks... Hanging a white light above them may give a little bit of warmth from the white rays, but most of the energy goes into heating the air around the bulb which just raises to the ceiling.
A white light will work in a smaller container. Especially one that is partly covered or under a hover that will trap the rising heat.
Temperature control is really not all that crucial. Give them a warm area and a cooler area. They adjust themselves as necessary. If they are piled up directly under the heat source, they need more heat. If they are crowded around the sides of brooder panting and trying to escape the heat, then obviously it's too warm.