What Should PA and NJ Pool Owners Do Each Fall?

TL;DR: Fall pool closing in PA and NJ involves balancing chemistry, lowering the water level, blowing out all plumbing lines with compressed air, draining and protecting all equipment, adding winterization chemicals, and installing the winter cover. Done correctly, nothing freezes and the pool opens clean in spring. Done incorrectly, cracked pipes, damaged equipment, and a green mess at opening are the result. Professional closing costs $350–$600 and is the single best investment in preventing expensive winter damage. Scott Payne Custom Pools recommends professional closing for at least the first year for all PA and NJ pool owners.

Fall closing is the most technically demanding maintenance event of the PA/NJ pool year. The consequences of doing it wrong are severe — frozen plumbing, cracked equipment, algae growth under the cover — and they don't reveal themselves until spring when repairs are needed before you can swim. Getting closing right protects everything you invested in the pool and ensures a smooth opening the following season.

Here's the complete fall closing process, sequenced correctly for PA/NJ freeze-thaw conditions.

Timing: When to Close

The conventional wisdom in PA/NJ is to close when overnight temperatures begin consistently dropping below 50°F — typically mid-to-late October for most of the service area. The strategic argument for closing later rather than earlier: warm water temperatures accelerate algae growth under winter covers, meaning pools closed in late September are more likely to open green in spring than pools closed in October when water temperatures are naturally cooler.

The practical signal: When you've swum for the last time this season and water temperatures are dropping below comfortable swimming levels (below 65°F for most people), it's time to close.

Step 1: Final Chemistry Balance (1–2 Days Before Closing)

Close the pool with chemistry in proper ranges, with pH slightly on the lower end (7.2–7.4 rather than the normal 7.4–7.6 target). Slightly acidic water is less likely to scale during the winter and provides better protection for the interior finish.

Before closing, verify: - pH: 7.2 – 7.4 (slightly low end of normal range) - Total Alkalinity: 80 – 120 ppm - Calcium Hardness: 200 – 400 ppm - Free Chlorine: 3 – 5 ppm (higher than normal for extended coverage) - Cyanuric Acid: 30 – 50 ppm

Add winterization chemicals: - Winter algaecide (a long-duration algaecide formulated for winter conditions, typically a 90-day formula) - Stain and scale preventer (particularly important for pools in high-mineral areas) - Optional: sequestrant if your water has elevated metal content

Do not add these chemicals through the skimmer — add directly to the pool water in front of a return jet with the pump running to distribute.

Step 2: Lower the Water Level

Lower the pool water level to below the return jets and below the bottom of the skimmer opening. The specific level depends on your closing method:

• Mesh winter cover: Lower 12–18 inches below coping (allows rain and snowmelt to enter through the cover without overflowing)
• Solid winter cover: Lower 3–6 inches below the skimmer opening

The water level should not drop so low that the pool shell interior is exposed above the waterline — this dries out plaster and can cause damage over winter.

Lower the water level using the filter backwash valve (if you have a sand filter), a submersible pump, or by opening a waste valve if your system includes one.

Step 3: Blow Out All Plumbing Lines

This is the most critical and technically demanding step. Every drop of water in every plumbing line must be removed. Water left in plumbing expands when it freezes and will crack PVC pipe — often in locations that are buried and inaccessible without excavation.

Equipment needed: Air compressor capable of 30–50 CFM (not a small pancake compressor — a larger tank compressor or a dedicated pool blower), winterizing plugs for each return jet and skimmer.

Sequence: 1. With the pump off, connect the air compressor to the pump's inlet fitting (using an appropriate adapter) 2. Close the main drain valve (if accessible) 3. Blow air through the skimmer lines until only air exits the skimmer bodies 4. Plug each skimmer with a winterizing plug 5. Redirect airflow to blow through the main drain line (if you have a 3-port valve) 6. Close the main drain valve 7. Redirect airflow to blow through return lines until only air exits the return jets 8. Plug each return jet with a winterizing plug 9. Blow any remaining water from auxiliary lines (spa jets, water features, fountains) 10. Verify all lines are blowing only air before plugging

Add non-toxic antifreeze (propylene glycol) to any line segments that cannot be fully drained — typically the last few inches of plumbing before a plug or fitting. Never use automotive antifreeze (ethylene glycol) — it is toxic to pets and wildlife and damages pool surfaces.

Step 4: Drain and Winterize Equipment

Pump: Remove the drain plug from the pump housing to release any remaining water. For variable-speed pumps, the pump housing often has a drain plug and a separate strainer lid — drain both. If your pump is in a location exposed to hard freezes, remove the pump basket and leave the drain plug out.

Filter: - Cartridge filter: Remove cartridges and allow to dry. Clean thoroughly with a cartridge cleaner. Store cartridges indoors or in an unheated but frost-protected space. Remove the drain plug from the filter housing and leave it out. - Sand filter: Open the backwash valve to its drain position or remove the drain plug. For multi-port valves, set to "winterize" or "blow out" position if available. - DE filter: Backwash until water runs clear, then drain completely.

Heater: - Gas heaters: Turn off gas supply. Remove the drain plug from the heater's heat exchanger housing. Some heaters require removal of an access panel to locate the drain plug. Verify no water remains in the heat exchanger. - Heat pumps: Most heat pumps drain automatically when power is off, but verify the manufacturer's winterization instructions for your specific model.

Chlorinator or salt cell: Remove any tablet feeder from service and store remaining tablets indoors. For salt cells, remove the cell from the plumbing (most slide out with a quarter-turn) and rinse thoroughly. Store the cell indoors or in an unheated frost-protected location.

Step 5: Install the Winter Cover

Mesh covers: Allow rain and snowmelt to drain through while keeping debris out. These are standard across much of the PA/NJ market.

Solid covers: Block all light and water entry. Require a cover pump to manage water accumulation on top.

Install the cover tightly, ensuring no gaps at the edges where debris can enter. Secure with water bags (for most covers), cable and winch systems, or anchor systems depending on cover type.

Step 6: Final Checklist

Before walking away for the winter:

✓ All return jets plugged with winterizing plugs ✓ All skimmers plugged with winterizing plugs ✓ All equipment drain plugs removed and/or stored indoors ✓ Water level at appropriate winter level ✓ Heater gas valve turned off ✓ All electrical circuits turned off at the panel (or automation system set to winterize mode) ✓ Winter cover installed and secured ✓ Pump basket and any removed filter cartridges stored appropriately

Frequently Asked Questions

Can I close my pool myself, or should I hire a professional?

For first-year owners and for pools with complex plumbing configurations, professional closing is strongly recommended. The blow-out process requires appropriate equipment (a commercial-grade air compressor, the right adapters) and specific knowledge of your pool's plumbing layout. A missed line or an inadequate blowout can result in $3,000–$8,000 in freeze damage. Professional closing at $350–$600 is inexpensive insurance. After experiencing professional closing once and watching the technician work, many owners feel comfortable handling it themselves in subsequent years.

What happens if I close too early in September?

Warm water temperatures under a dark winter cover create ideal algae-growing conditions. Pools closed in warm water (above 70°F) with limited algaecide coverage frequently open in spring with significant algae growth that takes multiple shock treatments to resolve. If circumstances require an early closing, use a heavy-duty 90-day algaecide, maintain higher-than-normal chlorine levels at closing, and consider adding a phosphate remover before covering.

Do I need to add antifreeze to my pool plumbing?

Properly blown-out plumbing doesn't need antifreeze in the main lines — if you've removed all the water with compressed air, there's nothing left to freeze. Antifreeze is useful in specific situations: plumbing runs that can't be fully blown out due to configuration, the last few inches before a plug or fitting where small amounts of water may remain, and skimmer bodies after plugging (add a cup of pool-safe antifreeze to each skimmer body as insurance). Never use antifreeze as a substitute for proper blowout.

Should I shock the pool before closing?

Yes. A shock dose 24–48 hours before adding algaecide and closing chemicals kills any active algae or bacteria. Add algaecide the day before or day of closing (not simultaneously with shock, as chlorine degrades algaecide rapidly). The closing chemistry sequence: shock, wait 24 hours, then add algaecide and stain/scale preventer, then lower water level and begin blowout.

---