I will take a try at the process. Sounds like water is being spilled over clay pot chards before entering the pond rather than a free fall out of a 3 inch pipe.
Water is "thin", having a lower viscosity than lets say honey. Water will deform in shape under shear stress. With fluid friction, water running over many flat surfaces, the water is "thinned" out. There is a much greater surface area in contact with atmosphere allowing greater respiration or gassing. So water viscosity allows for thin sheeting, if the situation allows, which in turn allows for higher respiration. There ia a new filter manufactured in Europe the works on this principle.
