I do follow the instructions for the incubators and add water to the second channel 3 days before hatch, but I also never use a hygrometer in my incubators. I usually have 8 or 9 running at once (hovabators) There are so many people that have lousy hatches and think its humidity, the reality is their thermometer is off. Think about it- in nature the only thing that is a constant and correct is the temperature under the hen,(unless the hen has a fever) lol. Humidity will vary depending on climate, surface the nest is on, weather conditions and so on, so variances in the humidity is not so important on a day to day basis. To answer the original question- the pipping chicks will raise the humidity automatically when they pip the moisture from their little bodies excapes, The combination of the hen setting tight and the pipping chick creats a more humid enviornment.