Sundance uses a unique filtering system. Water is drawn over the Slipstream™ skimmer to remove impurities and debris on many of the Sundance Spas Series. The Weir Assembly comes with an area built in for chemical dispensing or use of the Sunpurity. Other Sundance or Sweetwater Spas uses a skimmer assembly for skimming off the oils and contaminants that float to the water's surface. We also carry the components for the weirs and weir baskets for Sweetwater and Del Sol Spas.