Dry incubation in the winter

Dry
incubation worked
well for me last summer, but within a day of starting this year’s first
incubator run, I could tell I needed to make some changes.  I
noticed last year that keeping the humidity in the incubator in the low
thirties ensured proper egg weight loss, and the summer air was so damp
that the right humidity was easy to achieve without adding any water to
the wells of the incubator.  However, when I plugged in the
incubator this February, humidity was in the teens to low twenties —
too dry even for dry incubation.

I filled one of the
wells with water after the first day and the humidity rose to hover
between the high twenties and low thirties.  But when I weighed
my eggs at the end
of day two, I could tell the eggs were still losing water too
quickly.  So I filled the second well part of the way up with
water to boost the humidity into the forties for a short time.

As the weather warmed up
outside, humidity in the incubator also rose.  Soon, filling only
one well was enough to keep the interior humidity around 35%, and my weight
loss spreadsheet
started to show more optimal weight loss.

The moral of the story
is — dry incubation is very weather dependent, so focus on the
humidity levels in the incubator, not the amount of water you add to
the wells.  Now I’ve just got to wait another week and a half to
see how well my humidity manipulation worked.