Demand feeder spout for small pellets

I'm trying to make a demand fish feeder around the core of http://www.thingiverse.com/thing:34100. This piece is untested as I left my filament in the office, but is meant to go on the end of the 2" PVC tee and prevent the small pellets from leaking out, while funnelling what the auger actively pushes out into a 3/4" poly tube which will direct them into the fishtank.

Add a pull string attached to a momentary switch and some Arduino code, and hopefully my fish will be able to feed themselves