Hi, the tube is 6mm PVC going through 6mm electrical glands. It shows the inside water level at a glance, otherwise I would have to take the lid off to check it.
Houses 12 chickens without issue. We are going to add on to the run portion and raise the run upward to allow us to walk in and not have to bend to clean. Made from 2x4's and plywood didn't take to long to build. Inside the roost is an 8" closet rod. Nest box's are milk crates with bottom cut out except for about 2 inches to prevent the girls from rolling the eggs out.