Obviously a newbie here. This is my first hatch. I am making it difficult on myself with a staggered hatch (4 actually) but I do have a separate incubator for lockdown. The problem is, at 12 days my oldest eggs have air sacks the size of 18day eggs. I live at 5400 ft elevation. The eggs came from much lower elevation; Florida, TN and Ga. I do have 8 from near me though. I have THREE hygrometers. I calibrated all three at different times using the salt method. 1 was +3%, 1 was -10% off and one was spot on. Put them in the incubator, add a tiny bit of water and the first two read 40% (taking into account the +/- factors). I order the third one. It just came in. I calibrate it the same way, put it in the incubator and it reads 10% humidity!! Now normally I would take this one and throw it out the window but when I candled those first eggs, the air sack is very large. This is SO frustrating. I have 29 viable eggs. The oldest ones have bouncing baby chicks inside and I'm afraid that I have already destined them to a shrink wrap hatch. Should I increase the humidity for the rest of the incubation (before lockdown). Can you actually DECREASE an air sack or is it too late? Pulling my hair out here at 5400 ft! And I want to thank eveyone on this forum for all the tips and advice I get from here.