[Madmak]

A true Bean Animal is a combination of safety and low noise. The full siphon starts and ends under water, very quiet. The secondary also starts and ends under water but is meant to carry very little water, also very quiet. The airline vent is a safety measure to allow the secondary to become a full siphon if the water level rises above the vent line. The third pipe is purely an emergency and stays dry. If you hear this pipe it is time to find a problem.

I love the design.