Two communicating tanks having an additional outlet

Description

Three tanks—two wider ones and a narrow one—are connected by hoses as follows. The wider ones feed into the narrow one, and the latter has an additional outflow.
The idea of this experiment is to show how the level in the narrow tank changes very quickly compared to the levels in the other two tanks. If we could make the third tank as narrow as we wished, it would resemble more and more a pure junction of pipes (the two hoses draining the larger tanks joining into a single hose).
With a very narrow tanks, we would have a system with strongly differing time constants making simulation more demanding.