The pvc has to be shortened to work. The feed doesn't move up inside. The cut grooves simply allow the feed to flow into a shallow layer inside. The bigger the holes, the deeper the layer. You don't want the layer too deep, just enough for good flow. The points keep the pvc stable on the bottom of the bottle.Thank you! I am going to try this today. I'm glad for the picture, I wouldn't have thought it would be able to move up through that big of a turn - mine probably would have all dumped out!
I have the watering cups now (also spring loaded) and they work great. I am still giving them both kinds of waterers but they don't even seem to notice when I change the old ones any more and they used to swarm it for clean water every day.