Pool closing season is one of the highest-revenue periods of the year for pool service companies in colder climates. Done well, winterization protects expensive equipment and surfaces from freeze damage and positions your company as the obvious choice when opening season arrives. Done poorly, a missed drain port can cost a client thousands and your company a loyal customer.
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Chemistry Balancing Before Closing
Chemistry preparation before closing is more critical than many technicians realize. The pool water will sit untreated for five to seven months in cold climates, and the chemistry balance at closing determines what you will find in the spring. Start the closing chemistry process two to three weeks before the scheduled close date to allow time for adjustments. Target pH between 7.4 and 7.6, total alkalinity between 80 and 120 ppm, and calcium hardness between 200 and 400 ppm. These midrange values give the chemistry stability throughout the off-season without trending toward scale or corrosion. Chlorine is particularly important at closing. Shocking the pool with a full dose of liquid chlorine or granular shock at closing elevates free chlorine enough to suppress algae through the critical early dormant period when temperatures are still warm enough for growth. A well-shocked pool at closing should show residual free chlorine well above 5 ppm at the time of service. Many technicians add a pool closing chemical kit, which typically includes a concentrated algaecide, a stain and scale preventer, and sometimes an enzyme product. These kits provide residual protection that supplements the chlorine shock. Always add the algaecide last, after the shock chlorine has been added and broadcast, because simultaneous addition reduces the effectiveness of both products. Stain and scale preventer is particularly valuable in pools with high calcium or iron in the source water, as off-season evaporation and concentration effects can cause staining without the dilution and chemical management that occurs during the active season. Test the pool water after closing chemistry additions, confirm that all parameters are in range, and document the closing chemistry values in your service records. Clients who ask about their opening condition in spring will appreciate the documented baseline, and it protects you if any off-season issues arise.
Equipment Blowout and Drain Procedures
The equipment blowout is the most technically demanding part of pool winterization, and incomplete blowouts cause the majority of freeze damage claims. Water expands roughly 9 percent when it freezes, and any residual water trapped in a pump housing, heater heat exchanger, filter, or plumbing line can crack or rupture that component. The goal of blowout is to remove all standing water from every component in the circulation system. Start by draining the pump, filter, heater, and any other equipment that has drain plugs. Remove all drain plugs and keep them in a labeled bag stored in a visible location at the equipment pad so they are easy to find at opening. Never leave drain plugs in place over winter in freeze climates. For underground plumbing, blowout requires a commercial-grade blower or a large compressor capable of maintaining continuous pressure and flow. Starting at the equipment pad, blow each return line from the pad through to the pool returns. You will know water has been cleared when bubbles come out of the return fittings in the pool. Blow each suction line from the pad through to the skimmer or main drain as well. Plug each fitting at the pool end as you complete it, using winter plugs or gizzmo-style plugs that float inward to accommodate any residual ice movement. The main drain requires particular attention in areas with deep freeze risk. If the main drain line cannot be fully blown clear, at minimum ensure that the line is capped at both the pool end and the equipment end so no water can enter from either direction and freeze in the line. Heaters must have their internal drain plugs removed and the header flushed. On gas heaters, also drain the pressure switch port. Salt cells must be removed, cleaned, and stored indoors above freezing temperatures. Storage at freezing temperatures does not damage the cell if it is dry, but storing it wet risks the plates cracking.
Cover Installation and Service Pricing
Pool cover installation is the final step of winterization and the one most visible to the client. A well-installed cover that fits properly and is tensioned correctly looks professional and provides effective protection. Solid safety covers with anchor straps are the current standard in most markets and provide significantly better protection than traditional floating covers or water bag covers. Before installing the cover, remove all accessories from the pool including ladders, steps, handrails, and skimmer baskets. Confirm the water level has been lowered to the appropriate depth for the cover type, typically 12 to 18 inches below the skimmer opening for mesh covers and closer to 6 inches for solid covers. When installing a safety cover, follow the manufacturer's pattern for anchor strap tension. Overtightening the anchors puts excessive load on the cover material and the anchor hardware. The cover should be drum-tight but not under maximum tension. Check the anchors for any that are loose in the deck and tighten or replace them before installing the cover. Pricing pool closing services profitably requires accounting for travel time, labor time, chemicals, blower rental if you do not own a blower, and any consumables like plugs, gizzmos, and cover bags. A residential winterization in a typical market ranges from 200 to 500 dollars or more depending on pool size, equipment complexity, and local labor rates. Larger pools with complex plumbing, multiple water features, and commercial-grade equipment take significantly longer and should be priced accordingly. Consider offering an early booking discount for clients who schedule in advance, which allows you to optimize your routes and manage the compressed closing season more efficiently. Bundling winterization with the following spring opening at a package discount also increases retention and locks in revenue before the season begins.
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