Just a what if.
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welcome to BYC, your alarm wont go off? and it doesnt hold more water than this? And are you certain you want to run at this humidity level?
I am going to throw a paste from the incubation with friends thread on here for now in case I cant get back with you...... its were I am most times and many others... there is info in the link as well on humidity
see if there's a way to reprogram the humidity alarm and set it to 25%. High humidity causes more problems with first time hatchers than low humidity due to the humidity affecting the size of the air sac. If you are running a true 65% humidity for the incubation period the chances are the air sac will be small so when the chick internally pips it will drown before hatching. Lower humidity is safer for new people to use 35-50% would be fine if you can work out how to disable the alarm.
A few tips.
humidity works on surface area so it doesn't matter how deep the water its the amount of surface area that controls the humidity.
The affect of humidity is averaged over the incubation period so a few hours or even days at a high or low level is not the end of the world as long as the air sac is about the right size just before lock down. (do a internet search to find a chart showing air sac to age on incubated eggs).
During lock down you do need to increase the humidity up into the 70's so you may have to add a sponge to increase surface area.
p.s this advice is for chicken/quail eggs if you are doing duck eggs ignore everything ive said