You can open it. I usually cut up a few sponges & add them on day 18 this helps hold higher humidity. Best advice is don't open it when they start hatching let them all hatch before you open it .
Was browsing a former topic on humidity - which is now closed so can't ask there. Had an issue with quite a few eggs not hatching, referred to a trouble shooting that says low humidity is a factor. I don't have anything available but a cheap Acurite thermometer/hygrometer from TSC - but got one for next time. Then started looking for what it should be and read not over 50. Sitting here now it's between 40-50 for the last hour outside the brooder naturally. So how is that not enough humidity?
Have some Sussex in due yesterday - nothing yet. Really looked forward to these chicks but nothing...the first batch nothing's happened since last weekend - so I don't know what to change, how to change it or what it should do
I have a small piece of PVC pipe that runs from an outside hole to over a pan of water. Add hot water to the pan by pouring into the pipe. I'm shooting for 75 to 80% at lockdown. .........stan
High humidity is usually more of a factor with chicks not hatching than low humidity. With high humidity they will drown before piping. Low humidity they will pip but cant get out because the membrane sticks to them. With high humidity also the membrane gets thick and rubbery and almost impossible for them to get out of.