Water vortex display from SJ City Hall exhibition -- repair and upgrade

I built this project a few years ago with a friend to help get him interested in mechanical design. Later, the project was adapted for display at a "tech and art" exhibition at San Jose City Hall. After 8 months, the painted steel impeller began to rust and discolor the water in the tube. I took the device back to my shop and replaced the original aluminum shaft with a stainless steel shaft, replaced the shaft seal, and changed the impeller to an all-plastic design. If I were designing the device again, I would opt for a spring-loaded PTFE (Teflon) shaft seal, which I have used with great success in other applications.

Drill motor control:
http://www.youtube.com/watch?v=7yEABsNyRfo

Original video showing the WiFi-controlled watering can and vortex tube:
http://www.youtube.com/watch?v=XKrlRJ-GJms