"Yes, I use 1/2 cup salt and 1/4 cup water in a cup, place the cup with the salt/water in a large ziploc bag and put the hygrometer beside it, seal it up an leave for 12 hours. After 12 hours it should (but probably won't) read 75%. Say it reads 62%--you'll have to add 13 to whatever it read in the incubator to figure out the right humidity. If it reads 80% after the 12 hours you know that you'll have to -5.
I did my digital the same way, it's consistant with my other hygrometer (they both read the same after I make the respective adjustments) so just make sure that the probe is in the bag along with the main unit and it should work fine."
This was cut and pasted from another post. It's a good idea to do it so you have a better idea. The salt should be like "wet sand"
Thanks Peeps! I'll have to do that right now I'm flying by the seat of my pants. Sorta a bad way to start out your first hatch but a lot of things happened this weekend so I meant to get it earlier but it just didn't happen...