â€¢ Sand Filters are large tanks filled with pool filter sand or media. They are very simple to use and require minimal maintenance. The functions of the sand filter are easily controlled through a Multi-Port Valve. Water from your swimming pool is pumped through the sand bed inside the tank, which filters out fine particles and other debris, before returning the water to your pool. In general, the sand or media should be replaced about every five years, based on usage.