It sounds like you've got the idea. You could experiment with a large paper cup and one of those straws that bend at the top or a piece of clear hose. The red dot in my illustration shows where you could locate a vent hole for further experimentation. Once the vent hole is added the water should only siphon down to the height of the vent hole. Keep in mind that once siphoning has begun, should the vent hole become plugged the water will drop until air enters the system at the intake. Basically emptying your pond if the intake goes all the way to the bottom.
