I, like many others, use the “no substrate” method you’re talking about. There are positive and negatives to this method.
Positive …
It’s easy to keep humidity perfect. You can see if the water is low and add if needed.
Less issues with mold or eggs getting too wet and rotting (on the bottom) in the substrate.
No set-up mixing or mess.
Negatives …
Eggs are not as protected against temperature changes. Therefore, incubator temperatures must be (and remain) consistent. I use a professional grade (Thelco) incubator that holds the temp perfect. It has a glass door, which I try to avoid opening.
Eggs are susceptible to rolling on the flat surface. I use a couple of strips of paper rapped around the eggs to prevent this.
I like the “no substrate” method… works for me.
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Larry Walker

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