One Simple Way to Winterize Your Pool
The Ultimate Step-by-Step Guide to Pool Winterizing
Preparing your backyard oasis for cold weather doesn’t have to be overwhelming. Taking a methodical approach ensures you won’t miss any critical steps. Before getting your hands dirty, gather your essential supplies checklist:
- Water testing kit or strips
- Balancing chemicals (pH increaser/decreaser, alkalinity increaser, calcium hardness increaser)
- Chlorine shock (preferably 65% calcium hypochlorite)
- Non-copper winter algaecide (60% concentration)
- Non-toxic propylene glycol pool antifreeze
- Winterizing plugs, expansion plugs, and skimmer guards (Gizmos)
- Wet/dry shop vacuum or low-pressure air compressor
- Air pillows (for above ground pools) or water bags/safety cover hardware (for inground pools)
Start with a deep, thorough cleaning of the entire pool. Brush all surface walls, tile lines, and floors to loosen micro-algae and debris. Skim off all floating leaves, and vacuum the floor thoroughly. If you have active algae, vacuum directly to waste rather than through the filter. Reviewing our 10 Pool Closing Checklist for Hassle-Free Winter can help keep your workflow organized.
Timing is everything. Closing your pool too early when water temperatures are above 65°F will rapidly consume your sanitizer, leaving the pool vulnerable to algae blooms under the cover. Wait until water temperatures consistently hover below 65°F—and ideally below 60°F, where algae growth naturally halts.
Water Chemistry Preparation for Pool Winterizing
Proper water chemistry forms the baseline for off-season surface protection. Test and adjust your water 3 to 7 days before final closing using this precise sequence:
- Total Alkalinity: Adjust to 80–120 ppm first. Wait 6 hours before moving to pH.
- pH Level: Balance between 7.2 and 7.6. Wait 4 hours.
- Calcium Hardness: Target 200–400 ppm for plaster and tile surfaces (180–220 ppm for vinyl liners).
Maintaining proper chemistry prevents extreme Langelier Saturation Index (LSI) shifts. As water temperature drops toward freezing, the LSI value naturally decreases, causing water to become aggressive and corrosive. Balancing water slightly positive on the LSI scale prior to closing offsets this natural downward drift, protecting plaster and metal fittings. Use a tool like the Pool Winterizing Calculator — Closing Chemicals & Doses to compute precise dosing for your pool’s capacity.
Chemical timing is vital: apply your chlorine shock (2 lbs of 65% cal-hypo per 10,000 gallons for clear water) at dusk to raise Free Chlorine to around 20 ppm without UV degradation. Run the filter pump overnight. The following morning (8 to 24 hours later, once free chlorine drops below 5 ppm), add your winter algaecide. Adding shock and algaecide simultaneously causes chlorine to destroy the algaecide instantly. For complete product choices, explore our guide on Pool Winterizing Closing Chemicals for Winter.
Blowing Out Plumbing Lines and Equipment Drainage
Water expands by about 9% when freezing. Stagnant water left inside underground pipes will split PVC lines and crack fittings, leading to thousands in excavation repairs.
To purge plumbing lines, connect a heavy-duty wet/dry shop vacuum (on blow mode) or a low-pressure air compressor to the main pump equipment pad. Blow air through the suction lines (skimmers and main drains) until air bubbles vigorously out into the pool. Insert tapered expansion plugs into skimmer ports and tighten them down. Thread specialized skimmer guards (Gizmos) into the skimmer bottom to absorb ice compression.
Next, blow air through return lines, water features, and cleaner lines, sealing return ports with rubber expansion plugs as air blows water clear. Pour 1 to 2 quarts of non-toxic propylene glycol pool antifreeze into each skimmer line for added insurance. Never use toxic automotive antifreeze!
Set multiport filter valve handles directly between settings (or to “Winterize”) to relieve pressure on internal gaskets and allow room for ice expansion within the valve body, adhering to APSP Winterizing Standards. Drain all water from filter tanks, pumps, heaters, and chlorinators by removing drain plugs. Store pump motors, salt cells, and automated sensors indoors in a dry area kept above 40°F.
Inground vs Above Ground Pool Winterizing Nuances
Inground and above ground pools require different structural protection strategies during winterization.
For above ground pools, properly inflating air pillows and anchoring them in the pool’s center is mandatory. As ice forms across the surface, it expands inward against the air pillow rather than outward against the rigid pool walls, preventing costly structural wall collapses. Read detailed steps in our guide on How to Winterize an Above Ground Pool.
In contrast, inground pools require careful drawdown control based on surface type. For additional inground insights, see How to Winterize a Pool Inground Pools. Mesh covers allow rainwater and snowmelt to accumulate, requiring a lower water level to prevent mid-winter overflow, while solid covers displace water differently across the pool top.
Protecting Pool Equipment, Covers, and Avoiding Pricey Mistakes
Choosing and Installing the Right Winter Cover
Selecting the right cover setup shields your investment against leaves, debris, and structural damage over the long off-season.
- Solid Tarp Covers: Inexpensive ($30–$200), light, and effective at blocking sunlight and fine debris. They require water bags placed perimeter-wide and sub-pumps to clear standing rainwater.
- Mesh Safety Covers: Anchored into concrete decks via spring-loaded brass anchors ($300–$900). Super durable, holding heavy snow loads while allowing water to pass through.
- Solid Safety Covers: Premium option ($600–$1,500) lasting 10–15 years. Completely blocks sunlight to eliminate algae growth while offering total safety for kids and pets.
When securing tarp covers on inground pools, fill water bags 1/2 to 3/4 full (leaving room for freezing expansion) and space them end-to-end in high-wind regions. For above ground covers, tighten the perimeter steel cable using a heavy-duty winch system.
10 Critical Pool Closing Mistakes to Avoid
Avoiding operational blunders during winterization saves time, money, and headaches. Check out our detailed overview of 10 Common Pool Closing Mistakes to Avoid.
- Closing when water is too warm: Accelerates sanitizer consumption and invites green algae growth.
- Mixing shock and algaecide together: High chlorine levels destroy algaecides instantly.
- Completely draining the pool: Hydrostatic pressure can pop an empty fiberglass shell or crack concrete.
- Skipping line blowouts: Trapped water freezes, causing split pipes ($500–$2,000+ repair costs).
- Using automotive antifreeze: Toxic to humans and ruins pool chemistry.
- Leaving drain plugs in equipment: Trapped water splits pump housings and filter bodies.
- Neglecting pH and alkalinity adjustments: Acidic water corrodes metal fixtures; alkaline water scales plaster.
- Using cinder blocks to weigh down covers: Tears vinyl liners and damages pool decks if pulled in.
- Ignoring high Cyanuric Acid (CYA) levels: High stabilizer ruins closing shock efficiency.
- Neglecting mid-winter cover maintenance: Heavy snow buildup damages safety cover springs and straps, causing future Pool Equipment Problems After Winter.
Winter Maintenance, Kits, and Non-Freezing Climate Strategies
Mid-Winter Checks and Chemical Winterizing Kits
Winter pool care doesn’t stop once the cover goes on. Performing simple mid-winter checks preserves water clarity for spring. At least once a month, peel back a corner of your cover to inspect water level and clarity.
Using a chemical winterizing kit simplifies off-season maintenance. These multi-stage systems frequently feature slow-release, floating treatment dispensers filled with non-copper algaecides and clarification agents designed for pools up to 30,000 gallons. The treatment floating dispensers float vertically in the water column, dispensing sanitizing agents for months as temperatures fluctuate.
If you notice chlorine levels dropping below 3 ppm, pour liquid chlorine beneath a cover corner to maintain adequate sanitizer residual, taking care not to stain vinyl liners. For detailed guidance on step-by-step closing routines, read this external Winterizing a Pool: Step-by-Step Closing Guide. Always remove heavy snow accumulation from pool covers using a soft broom—never heavy shovels or sharp tools that could puncture the material.
Winter Pool Care in Non-Freezing Sunbelt Climates
If you live in a region that rarely experiences hard freeze conditions, complete pool winterizing isn’t necessary. However, off-season care still requires slight adjustments.
Reduce pump run times from summer durations down to 2–4 hours daily during off-peak hours to conserve energy while keeping water moving. Ensure your system’s freeze-protection automation is working so pumps kick on automatically if ambient temperatures drop near 32°F. Test water monthly, maintain 2–4 ppm Free Chlorine, and brush walls periodically. For additional non-manufacturer guidance on off-season pool care, review our Tips to Battle Pool Algae Winter Pool Care SOS.
Frequently Asked Questions About Pool Closing
When is the right time and temperature to close a pool?
The ideal time to close your pool is when water temperatures consistently drop and stay below 65°F—ideally below 60°F. Algae lies dormant below 60°F, preventing rapid chlorine depletion beneath the cover. In Northeastern Pennsylvania, this temperature drop usually happens between late September and late October. For region-specific timing tips, check out our article on the Best Time to Close an Above Ground Pool in PA.
Why shouldn’t you add pool shock and algaecide at the same time?
High concentrations of chlorine shock instantly oxidize and destroy algaecide compounds on contact, rendering both products ineffective. Shock the pool at dusk to super-chlorinate the water, run the pump overnight, and wait 8 to 24 hours until free chlorine drops below 5 ppm before pouring in winter algaecide.
How do 3-in-1 winterizing kits simplify off-season pool care?
All-in-one winter closing kits eliminate complicated dosage calculations by combining winter shock, slow-release algaecide, and stain/scale inhibitors in pre-measured formulas. Many kits feature drop-in, slow-release dispensers designed to sink or float across pools up to 30,000 gallons, steadily releasing protective chemicals over multi-month periods to prevent green pool water.
Enjoy a Stress-Free Spring Opening with Expert Winter Preparation
Proper winterizing protects your equipment, keeps your water clear, and saves you thousands in potential freeze repairs. Taking 2 to 4 hours in the fall ensures a smooth, stress-free spring opening when warm weather returns.
If blowing out lines or handling heavy covers feels overwhelming, let our experienced team handle it for you. With over 50 years of pool service experience across Luzerne County, PA (including Luzerne and Shickshinny), Skovish Pools & Spas offers comprehensive, professional winterization services. Learn more about our options in our review of the Best 2024 Pool Closing Services in PA, or visit our guide on Pool Winterizing Closing Chemicals for Winter to stock up on all your closing supplies today!
