A piece of bamboo is hinged on a small post at a T. It is longer and heavier on one side and because of this it tilts. Water flows into one side and fills up that side. That side grows heavier than the other side and tilts and dumps the water into the resevior. When this side drops the other side raises and knocks something, making a "goonk" sound. These fixtures are sometimes found in Japanese Zen gardens and Ive heard that they are also used as a wildlife repelant. Please help