I can never really manage to get my humdiity above 60 anyway and havn't had an issue before with that being too low, it was just with this brand new bator that I built and tried for the first time. I actually incubated them to day 14 in my Roll x and used the coolerbator as a hatcher, so if I'd used the cooler for the whole incubation period i might have ended up with even less. And one of the chicks I pulled from the shell couldn't right himself when he dried off. Ironically enough one of the vets in the building said it looked like oxygen deprivation in other newborn animals...