I have incubated Russian Tortoise eggs without success for the past 4 years. I believe that the eggs have not been fertile in the past, but I'm beginning to wonder if it's the use of a fan in the incubator that is the problem. I have used a Hovabator with the turbofan and also an R-com Juragon which has an air circulator. I keep seeing the term "still air" being used. Should I disconnect the fan in my Hovabator? The temperature and humidity have always been strictly monitored.