Place the thermometer at a level or slightly above, where the center of the egg will be. Although a short cooling period may not be harmful, long periods of low temperatures will slow embryo growth. Very low temperatures will kill the embryos. Avoid temperatures outside the 97 to 103 degree F range. Fewer eggs will hatch if the temperature is either too high or too low for several days.
Moisture is provided by a pan of water under the egg tray.
Add warm water to the pan as needed. To boost humidity, increase the size of the pan or add a wet sponge. You can also adjust the humidity by adding or cutting back on airflow. If you don t have a wet bulb thermometer, you can check humidity by noting the size of the air cell in each egg. The air cell grows during incubation at a certain rate based on temperature and humidity.