What I have did for humidity is I add 1/4 a cup everyday (my ambient humidity is beyond low in my house) through day 18, this keeps my humidity between 30-50%. When I go into lockdown on day 18 I added 1/2 cup to it and if the humidity starts to fall below 60% I lift just one end enough to quickly add another 1/2 cup, I usually only have to do this once and humidity stays up as hatching starts. Another thing I noticed is around day 10 with this incubator the temp rises, I believe it is because the embryos are now producing their own heat, I leave the temperature alone the incubator will self regulate to bring it back down to the temperature you have it set at.