How to Winterize a DE Pool Filter: A Safe Step-by-Step Guide
Quick answer
To winterize a DE pool filter, turn off and disconnect power, relieve pressure, clean the DE grids, drain every drop of water from the tank and connected equipment, remove or loosen drain plugs as your manufacturer specifies, and leave the filter dry with the air-relief valve open. Do not store a DE filter with dirty grids or DE powder sitting inside it: trapped water can freeze and crack the tank, while leftover DE can harden on the grids.
Quick answer
How to Winterize a DE Pool Filter: A Safe Step-by-Step Guide: Quick answer To winterize a DE pool filter, turn off and disconnect power, relieve pressure, clean the DE grids, drain every drop of water from the tank and connected equipment, remove or loosen drain plugs as your.
This guide is for seasonal pool closing in climates where equipment can freeze. Always follow the manual for your exact filter model, especially for multiport valves, push-pull valves, separation tanks, and winterizing plugs.
What you will need
- Garden hose with a gentle spray nozzle
- Filter-cleaning solution approved for DE grids
- Safety glasses and chemical-resistant gloves
- A clean bucket or drain area
- Manufacturer-approved replacement O-rings or drain plugs if yours are damaged
- A pool test kit or the Pool Chemical Calculator app for the closing-water chemistry
For supplies, see DE filter cleaning products on Amazon and pool winterizing supplies on Amazon. As an Amazon Associate, we earn from qualifying purchases.
Before you start: balance and clean the pool
Winterize the filter after the pool water is balanced and the pool has been cleaned. Test and adjust pH, alkalinity, calcium hardness, and sanitizer before closing. Shock according to your closing plan, then let the water circulate long enough to distribute the treatment.
The filter itself should be cleaned before it is drained. Pentair’s filter guidance specifically warns against winterizing with DE precoat or residue left on the grids or in the tank. Your model’s manual controls the exact disassembly and cleaning method.
How to winterize a DE pool filter
1. Shut off the pump and isolate the equipment
Turn off the pump at the time clock and disconnect power at the breaker or disconnect when your equipment layout requires it. Never open a pressurized filter. Close isolation valves only if your plumbing configuration calls for them, and note their normal positions before changing anything.
2. Relieve all filter pressure
Open the manual air-relief valve on top of the filter slowly. Wait until the pressure gauge reads zero and no water or air pressure remains. If pressure does not drop, stop and have the system inspected rather than forcing a clamp, lid, valve, or plug.
3. Remove the old DE by backwashing or draining as designed
If your filter system uses a multiport or push-pull valve, perform the normal backwash and rinse sequence for that model before opening the tank. Follow local rules for discharge water. A DE filter should not be left with a used DE coating on the grids over the winter.
4. Open and clean the filter tank
With the pressure at zero, open the tank according to the manufacturer’s instructions. Remove the grid assembly only if the manual permits it and you can lift it safely. Rinse the grids from top to bottom with a garden hose until the water runs clear. Do not use a pressure washer: it can damage the fabric and seams.
For stubborn oils or scale, use a filter cleaner made for DE grids, allow the label-specified dwell time, and rinse thoroughly. Inspect the grids, manifold, tank seal, clamp, air-relief assembly, and pressure gauge. Replace cracked, torn, swollen, or badly scaled parts before spring startup.
5. Drain the tank completely
Open the filter tank drain plug or drain valve and leave the air-relief valve open so air can enter as water exits. Tilt or gently handle removable components only as the manual allows. Empty the pump strainer housing, heater, chlorinator, and other low points in the circulation system as part of the complete pool closing procedure.
Do not reinstall a drain plug tightly if your manufacturer says to leave it out for winter. Some models use a specific winterizing plug or storage position; others require the plug to remain loose or removed. Follow the exact model manual.
6. Blow or vacuum plumbing lines if your climate requires it
In freezing climates, winterizing the filter alone is not enough. Clear water from the suction and return lines with an appropriate pool-line blower or shop vacuum used according to the equipment instructions. Plug lines after they are cleared, and protect exposed valves from collecting water.
Never pressurize plumbing beyond the rating of the equipment. If you are unsure which line connects to the DE filter, hire a pool professional; a cracked underground line is far more expensive than a closing visit.
7. Leave the filter dry and protected
After draining, keep the tank open to ventilation in the way your manufacturer recommends. Store removed grids indoors only if the manual permits and the parts are fully dry. Keep the clamp, lid, drain plugs, and small fittings together and label their locations.
Cover the equipment pad from falling leaves without sealing in moisture. Do not restart the pump until every plug, valve, lid, and line has been returned to its spring operating position.
Common DE filter winterizing mistakes
- Leaving DE on the grids: Used DE and debris can harden and make spring cleaning harder.
- Skipping the air-relief valve: A closed air valve can trap pressure while you open the tank.
- Removing the lid while the gauge shows pressure: This is a serious safety risk.
- Using a pressure washer: High pressure can tear the grids.
- Draining only the tank: Water may remain in the pump, heater, chlorinator, valves, or plumbing.
- Adding pool antifreeze without checking the manual: Some products and systems are incompatible, and antifreeze does not replace proper line clearing.
- Forgetting what changed: Photograph valve positions and label plugs before closing the equipment.
DE filter winterizing troubleshooting
The filter will not drain
Confirm the pump is off, the breaker is isolated, the air-relief valve is open, and the drain plug is fully removed. If water still will not leave, check for a blocked drain path. Do not drill, pry, or pressurize the tank.
The pressure gauge does not return to zero
Treat the filter as pressurized. Close the pump isolation valves if appropriate, open the air-relief valve carefully, and stop if pressure remains. A blocked air-relief valve or gauge can require service.
The grids are still coated after rinsing
Use a DE-compatible filter cleaner for oils or scale, then rinse again. If the fabric is torn or the manifold is cracked, replace the damaged part rather than relying on a winter chemical treatment.
Water returns to the pool when the system is off
That can indicate a valve, check-valve, or plumbing issue rather than a filter-cleaning issue. Mark the water level, inspect for a slow leak, and have the system tested before a hard freeze.
FAQ
Should I leave DE powder in the filter over winter?
No. Clean the grids and tank, then drain the filter completely. Pentair guidance says not to winterize with DE precoat or residual DE in the tank.
Should I remove the DE filter grids for winter?
Not always. Some owners leave clean grids installed; others remove and dry them according to the manufacturer’s instructions. The important requirements are that they are clean, undamaged, and not sitting in trapped water or old DE residue.
Do I need to open the air-relief valve when winterizing?
Yes, while draining, unless your exact manual specifies a different procedure. Opening it lets air replace outgoing water and helps the tank drain. Never open the filter until pressure is zero.
Can I use pool antifreeze in a DE filter?
Do not pour antifreeze into the filter tank unless the manufacturer specifically approves that product and use. Proper draining and clearing of the equipment and plumbing is the primary protection; follow your local closing procedure and the filter manual.
When should I recharge the filter with DE?
In spring, after the pool is opened, the filter is reassembled, leaks are checked, and the pump is running normally. Add the model-specified amount of fresh DE only after the system is operating in filter mode.
Make the closing chemistry easier
Closing a pool is a chemistry job as well as an equipment job. Enter your pool volume and test results into the Pool Chemical Calculator app to calculate the right dose for sanitizer, pH, alkalinity, calcium hardness, and stabilizer before the cover goes on.
This article is general educational information. Your filter model manual and local plumbing, discharge, and chemical-safety rules take priority.
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