Evidently you are not reading my statement in its entirety .Or not understanding it.
The directions the manual gives works perfectly in a controlled environment such as a air conditioned home.
I will give a example of there explanation. if you took a cap off a water bottle and filled it and set in your bator and it was the only water in it. your humidity would reach x (I do not know what X is because I do not know all of your conditions)
The bottle cap would evaporate very fast and you would have to fill it to maintain your desired humidity.
If you had a tall shot glass with the same size hole as bottle cap and filled it and put it in your bator the humidity would be the same because the surface area of water would be the same.
It would take much longer for the tall shot glass to evaporate.
This is why the amount or depth of water does not control humidity . The surface area does.
And this is why you can fill your water cell and cover it with aluminum foil and only leaving a small surface area open and control your humidity.
I am not saying my eggs will hatch.
But I am saying there directions on controlling humidity works.