Have the brisnea maxi advanced incubator - you full the water at the side and this goes through to the waterpot in the centre of the incubator. How do I know how much water is right for to keep humidity right?
If the incubator does not show what the humidity is you would be best getting a hygrometer to put inside your incubator then you can adjust the water accordingly. Humidity is created by surface area of water though and not depth in the pot. https://www.backyardchickens.com/articles/incubation-humidity.73386/