To further demonstrate that water can be sucked/pushed down try this. Take a clear piece of aquarium air tubing or any clear tubing a few feet long and completely submerse it in a bucket of water. While under water let all the air escape from the tubing and cap off one end with your thumb. Pull out the capped end and lower it below water level while leaving the other end in the water. Remove your thumb and allow the siphoning action to start. While the water is flowing, very quickly pull the end in the bucket out of the water and put it back in. You should see a pocket of air travel through the tubing and out the lower end.
