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Intermatic Support

How do I Winterize a Sand Filter?

Applies To

All Sand Filters

Question / Problem

How do I properly winterize a sand filter?

Safety Warning

Warning: Turn off the pool pump and all electrical power before servicing the filter. Always relieve system pressure before opening the multiport valve or removing drain plugs. Water under pressure can cause injury. Follow all manufacturer instructions and local codes.

Conditions

Winterizing a sand filter protects the tank, multiport valve, internal laterals, and plumbing from freeze damage. Proper winterization also prevents standing water, debris, or trapped contaminants from causing odors, staining, or algae growth when the pool is reopened.

Step-by-Step Resolution

  1. Backwash the Filter

    Turn the pump off. Move the multiport valve to Backwash, then turn the pump on. Continue backwashing until the water from the waste line runs clear. This removes debris that could cause odors or bacteria growth during winter storage.

  2. Rinse the Filter

    Turn the pump off and move the valve to Rinse. Turn the pump on and run for 30-60 seconds. This settles the sand bed and clears remaining debris from the plumbing. Turn the pump off when finished.

  3. Move the Multiport Valve to Winterize

    With the pump off, rotate the multiport valve to the Winterize position. This opens internal passages to allow full drainage and helps prevent freeze damage within the valve.

  4. Drain the Sand Tank

    Remove the drain cap or plug from the bottom of the filter tank to allow all water to drain out. Leave the drain opening unplugged during winter storage. Store the drain plug in a safe location for spring setup.

  5. Disconnect and Drain All Hoses

    Disconnect the hoses connected to the pump, filter, and multiport valve. Drain all water and allow components to dry completely. Store hoses, fittings, and accessories in a dry location to prevent cracking or mold growth.

Tips / Additional Notes

  • Proper winterization protects the filter tank, laterals, and multiport valve from freeze damage and helps ensure a smooth startup in the spring.
  • If your system includes a pump, heater, or chlorinator, follow each manufacturer’s winterizing instructions in addition to these filter steps.
  • In regions with mild winters, running the pump during freezing conditions may help reduce the risk of ice formation. Consult a local pool professional for climate-specific guidance.