In a gravity-fed system, only the vortex portion of the filter gains effeciency from the design. In a combination setup, the Vortex chamber removes primary solids and debris before the water is pumped to the main filter system (Big Sister, VistaClear, etc...). This setup has the advantage of allowing varying filter types to be used.
Vortex: The Vortex is used as a settling chamber. The water is drawn from a bottom drain in the pond and then enters through a tangential feed. The centrifugal force then pulls all the large waste materials to the outside wall. The large debris will then settle to the bottom and can be cleaned by opening the gate valve on the bottom of the Vortex Settling Chamber.
Filter: Water is pumped from the Vortex settling chamber to the chosen filter for finer debris removal before returning back to the pond.