Best PVC I saw that keeps waste down, prevents deer from passing saliva, all while not feeding non-deer species:
-Put a cap on the BOTTOM of the vertical large feeder pipe.
-Then drill a 1.5" hole in the bottom of that cap.
-Take an 24" long 1" piece of pvc. Fill with sand and cap both ends.
-Slide the 1" pvc into the large feeder pipe cap hole. With 12" inside the large feed pipe and 12" out.
-Run a stiff wire (like coat hanger) across the large pipe through small drilled holes, while passing the wire through the small holes in the top of 1" pvc. This allows the 1" to hang there while 12" is outside the pipe. It has a slight pivot to it.
-You can even tie a white piece of cloth to the 1" hanging outside if you want.
Now, hang the feeder up with the bottom of the pipe about 3-4 feet off the ground. The deer will come and get use to bumping the 1" pipe (where the rag can help- as they mess with it) which allows feed/corn to dispense from the 1.5" large feed pipe hole. Essentially, deer only get a little at a time, while other animals can not activate it.