I use an innertube for the hatch seal. I should sand it a bit where the molding lines are on the tube. It acts as a seal and a spring. Not sure if it will puff off or not but it is easy to stick your finger between it and the producer. Without the tube I needed a lid that fit the shape of the tank but with the tube I bet I could use different shapes and sizes. Maybe the part I cut out of the top of the tank.
And.
