I'm getting ready to put some chicks in my Little Giant 9200 Still Air Incubator tomorrow evening. I've had it on and am trying to regulate the temp. The question I have is regarding humidity. It didn't come with a hydrometer and says "The size of the air cell is the best guide to proper humidity." What are the thoughts of those of you who are more experienced with this (this is our first hatch). Should I buy a hydrometer? Or just check the size of the air cell? Thank you in advance!!!!