Comprehensive Guide: How To Winterize Sand Filters For Above Ground Pools
Proper winterization of an above ground sand filter requires complete drainage, removal of internal moisture, and the secure storage of sensitive components to prevent freeze-thaw damage. By removing the drain plug, winterizing the multiport valve, and protecting the pump, you ensure the integrity of the filter tank and plumbing systems through sub-freezing temperatures.
Essential Preparation and Equipment Checklist
Before beginning the winterization process, ensure you have the necessary supplies to prevent water retention within the filter housing. Residual water that freezes inside the tank or valve can expand, leading to hairline fractures in the thermoplastic housing or the blowout of gaskets and O-rings.
Essential Tools and Materials:
- Large adjustable pliers (channel-lock style) for union fittings.
- A shop vacuum or compressed air source (for blowing out lines).
- Food-grade silicone lubricant for O-rings.
- Replacement Teflon tape for threaded connections.
- A container or mesh bag for small hardware (drain plugs and gaskets).
- Winterizing plugs (if applicable to your specific pipe configuration).
Prerequisite Standards:
- Pool chemistry must be balanced before closing to prevent mineral scaling on the filter sand.
- The pool water level should be dropped to approximately 4 to 6 inches below the skimmer return if using a standard wall skimmer.
- Estimated duration: 60 to 90 minutes.
Step-by-Step Procedure for Winterizing Sand Filters
Step 1: De-pressurize and Power Down the System
Before manipulating any valves or loosening unions, verify that the pool pump is disconnected from its power source. Flip the circuit breaker dedicated to the pump to the OFF position. Open the air relief valve on the top of the sand filter tank to dissipate any residual pressure within the system. Failure to release pressure can cause water to spray forcefully when unions are disconnected.
Step 2: Flush the Filter Tank
Perform a backwash of the filter to clean the media. Once the water runs clear through the sight glass, switch the multiport valve to the RINSE position for 30 seconds to settle the sand. Turn the pump off again. This ensures that the filter sand is free of organic debris that could solidify or mold during the dormant winter months.
Step 3: Drain the Filter Tank
Locate the winter drain plug at the base of the sand filter tank. Unscrew it carefully. Ensure that you do not lose the O-ring or gasket attached to the plug. Allow all water to drain completely from the filter tank.
Pro-Tip: If the tank has a large amount of sand, place a piece of nylon stocking or a fine-mesh net over the drain opening to prevent the filter sand from washing out while the water exits the tank.
Step 4: Winterize the Multiport Valve
The multiport valve contains internal gaskets that are highly susceptible to freeze damage. Place the multiport valve handle in the WINTER position if available; if no winter position exists, leave the handle between two settings (such as between Backwash and Rinse) to prevent the internal diverter gasket from being compressed against the housing.
Step 5: Disconnect and Store Plumbing and Pump
Disconnect the hoses or PVC unions connecting the pool pump to the filter and the filter to the return lines. Open the drain plugs on the pump housing and the hair and lint pot. Use a shop vacuum on the blower setting to push any remaining water out of the lines back toward the pool. Once dry, store the drain plugs in a secure, labeled container attached to the pump or filter to ensure they are available for the spring startup.
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Technical Specifications and Winterization Parameters
The following table outlines the critical thresholds for maintaining filter system integrity throughout the winter cycle.
| Component | Maintenance Requirement | Storage Standard |
|---|---|---|
| Sand Filter Tank | Drain via bottom plug | Store outside covered or in a shed |
| Multiport Valve | Set to Winter position | Keep O-rings lubricated with silicone |
| Pump Housing | Remove all drain plugs | Store in a dry, climate-controlled area |
| Pressure Gauge | Remove if possible | Keep in a frost-free environment |
| Union O-rings | Inspect for cracks | Coat in silicone; store in a sealed bag |
Field Troubleshooting and Failure Remedies
Even with careful preparation, hardware can succumb to the elements. Below are common issues encountered during the winterization process and their professional solutions.
Stripped Drain Plug Threads:
- Root Cause: Over-tightening or cross-threading during the initial installation of the plug.
- Actionable Fix: Use Teflon tape to wrap the threads of a replacement plug before installation. If the tank threads themselves are stripped, apply an epoxy putty rated for underwater/plastic use to create a new seal, then replace the plug.
Residual Water Pooling in the Bottom of the Tank:
- Root Cause: The filter is positioned on a slight incline away from the drain plug.
- Actionable Fix: Carefully prop up the side of the filter opposite the drain plug using a wooden shim or brick to ensure gravity pulls the final dregs toward the drain port.
Difficulty Removing Pump Unions:
- Root Cause: Scale buildup and grit trapped in the union threads.
- Actionable Fix: Apply a penetrating oil to the threads and allow it to sit for 10 minutes. Use a strap wrench to exert even pressure on the union nut rather than using metal pliers, which may crush the plastic.
Frequently Asked Questions
Should I remove the sand from the filter during the winter?
No, it is not necessary to remove the sand from your filter for winter. As long as you have properly drained the water from the tank, the sand can remain in place throughout the winter months without causing damage to the tank walls.
Is it necessary to bring my pool pump inside?
While not strictly mandatory in all climates, bringing the pump indoors or storing it in a dry garage is highly recommended. Protecting the pump from moisture and sub-freezing temperatures significantly extends the life of the motor bearings and seal plate.
What happens if I forget to open the drain plug?
If you leave water in the filter tank, it will freeze and expand. Because thermoplastic tanks have little room for expansion, the pressure will often cause the tank to split or the internal laterals at the bottom of the tank to break, requiring a complete filter replacement.
Can I use antifreeze in my filter?
Generally, you should not put pool-grade antifreeze inside the sand filter tank. Antifreeze is intended for the plumbing lines to prevent them from bursting; adding it to the filter tank can lead to chemical degradation of the internal components and will simply be wasted.
Protect Your Pool Investment
Properly winterizing your sand filter is the most effective way to prevent costly equipment failure and ensure a seamless opening when the swimming season returns. Contact your local pool maintenance professional today if you suspect your system requires winterization assistance or part replacements before the first freeze.
