I have tried incbating at 50% and had zero hatch. I have tried "dry incubating, and had a very very poor hatch of dried out, sticky chicks. What has worked best for me has been to try to keep it around as close to 40% humiditiy the first 17 days and up to sixty, sixty five, between that, the last few days. Now my worst issue is with still air, and varying temps, so the eggs hatch sometimes days different from each other due to temperature differences in different parts of the incubator. Sooner or later I will get around to wiring a fan in my bators and I hope to solve that. Good luck with your hatching. You will figure out in time what works for you in your particular weather environment, work schedule, hatching setup, etc... Every setup is unique and you will find balance that works for you by making small adjustments here and there until you get your hatch rate up where you want it.