I have this incubator and once you remove the turner, the bottom is slick. Like mentioned before, you run the risk of splayed leg. I purchased some of the cardboard liners cut perfectly to fit once the turner is removed. I prefer non slip shelf liner that I cut to fit. I have used the liners as...
As for humidity, personally I like to keep it around 70% once there is an external pip. But I have bumped it up if I see a membrane drying out. Ducks take forever to hatch
What breed of duck? Do you have another calibrated thermometer in the Brinsea? If they are incubated at a higher temp, you can see early hatches. As far as the turner goes, I usually remove mine but one time I did place shelf liner down over the turner right before hatching. You'll have to be...