I placed a tiny rectangular tupperware in my Brinsea on my last hatch. I put a piece of paper towel in the tupperware and then added water to the container by bendable straw through the vent hole when needed (usually daily). The water helped with the humidity but my serama chicks could not drown because the paper towel absorbed most of the water. Once the chicks started to hatch I did not need to add water anymore since the humidity went up on it's own. The tupperware is above the chick in the photo.