I have read arguments for lower and higher humidity. Lower just makes sense in my head, and all I'm thinking is evaporation through those heavily painted shells, but there's no way to know what works for me until I try it. Since I only got 12 from this hatch, I will be setting at least 2 more. I will run the next one at 30%, compare results, then go from thereThis will increase oxygen and decrease C02. I wonder if the better hatches with low humidity are improved because of oxygen? Just a thought.