everywhere

Does anyone know how to regulate humidity in a incubator you need to pour water inside the tray directly under the eggs? I'm using the incuview https://www.amazon.com/gp/product/B0198U0XMM/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1 . I have 8 days left and my humidity has been going all over...