Drain Covers and Filters Socks for your Sundance. Diverter Valves can jam up with debris and grit, Sundance offers the Drain Cover Filters for certain years. After these years, Sundance did a redesign so that this problem would not occur. The socks slide over the Suction Cover and fit like a"sock". It is important to keep them clean of debris. If you notice noticeable decline in the Pump performance, check the filter socks along with cleaning the filter.