Still or Circulatied Air incubators?

[CowgirlHC]

Which is best and why? Does one hold a more stable temperature and humidity level over the other? Thanks!

 

[Ridgerunner]

Remember that a lot of chicks are hatched with both kinds. "Better" is a fairly subjective word, its meaning depending on your criteria. The more expensive ones and the ones used by professionals are generally forced air. Part of your answer may depend on cost and how often you actually incubate and how valuable those eggs actually are to you. Often eggs that have little value to us become precious treasures as soon as they go into an incubator.

Part of it depends on how it is made, but most forced air incubators will keep the same temperature and humidity throughout the incubator. Some, especially homemade ones, may have blind spots but usually not. Warm air rises and holds more moisture. You can get differences in temperature and humidity in a still air depending on where you take those measurements so measurement and control are a little more tricky. It's not so much that they don't hold temperature and humidity, just that it can vary depending on where you are in the incubator.

Because of the moving air, I think the humidity level needs to be a tad higher in a forced air, especially during hatch.

A forced air may return the entire incubator back to proper humidity and temperature levels after you open it, but I'm not real sure about that. It probably depends on how they are made. As far as I am concerned these drops in humidity and temperature during incubation are extremely overrated as problems. What is important in incubation is the average temperature and humidity, not an instantaneous humidity or temperature. A temporary drop in either is really insignificant.

During incubation, the chicks in the eggs need to breathe. The egg shell is porous so air can move through it. But they give off carbon dioxide. You need an air exchange to remove that build-up of carbon dioxide and replace it with fresh air. A forced air is better for that, but a still air with the vents properly placed and left open do a good enough job of that.