Should I increase the humidity for Hatching?

In general terms, it's good practice to increase humidity for the hatching period (days 18-21 of incubation). A figure of 70-75% relative humidity (RH) is a good target to have in mind. Higher humidity during the final three days of chicken incubation helps to soften the egg shells, making the hatch a less tiresome experience for the hatchlings.

Most incubators don’t feature automatic humidity control, and instead, rely on having two separate channels for the water. Having two channels helps regulate the evaporation, since water can only evaporate from the surface. Twice the channels means twice the evaporating surface, resulting in a higher level of humidity when all the channels are in use. An example of this is the Rcom 10 Pro, which has a circular humidity pot in the base of the incubator. The pot is split into two, allowing you to double or halve the surface area of water for greater control of humidity levels. Similarly, the Brinsea Ovation 28 EX features two separate trays in the yellow base of the incubator. You can just fill one channel, or fill them both, depending on how much evaporation you want.

And finally…less is better!

When it comes to chicken egg incubation, the No.1 mistake made by first time breeders is too much humidity. It’s vitally important to remember that embryos need air, not just moisture. Too much humidity will effectively suffocate the embryos and not allow them to fully develop inside the shells. So, when considering whether to add more water to the incubator, follow this simple rule… If in doubt, keep water out!