incubation without a humidity thermometer..help!

[Chickaroos]

Sad to say, I got here a little late. I have 24 eggs in a styrofoam incubator. I am on day 6 today. I candled last night and saw 21 had very visible network of blood veins and I could see their eyes starting to develop. (the other 3 eggs had little or no "action" going on) so anyway, I did not know I had to buy a humidity thermometer. I have the reservoirs filled half way with water, it has not ran dry yet (we live on the east coast, so its always really humid) I keep them in our spare bedroom with a constant temp. and I check the bator temp about a million times a day its been at a steady 99.6
What do I do about monitoring the humidity? or is it ok to play the guessing game?

 

[ChickenCanoe]

Weigh the eggs.
About half way down the page in the following link is a chart that shows weight loss of correct humidity.
http://www.brinsea.com/customerservice/humidity.html

 

[Chickaroos]

I broke down and just ordered one. Thanks for the tip! It was a good read! Thanks!