From APSP December 23, 2010

How a pool is closed for the winter will affect how easy it will be to open in the spring. The ultimate objectives in closing a pool for the winter months are to preserve water quality, protect equipment and surfaces and have the pool ready for enjoyment with a minimum of effort when opened. Proper closing helps to avoid costly issues such as freeze-thaw damage to pool surfaces, damaged or broken pool equipment and underground pipe damage. Improperly closed pools can lead to a costly and frustrating opening process. Whether a pool is completely closed or just put on reduced maintenance, it is important to be sure that the pool is not neglected over the course of the winter.

(1) Take care of any unresolved issues.

Any water-quality problems should be addressed before the pool is closed. Water problems that are not solved before closing will still exist upon spring opening. In fact, many of these problems can become worse over the course of the winter, which could make spring opening a real challenge. For example, a chlorine demand that is not satisfied before closing can continue to grow during the winter, especially in warmer areas.

(2) Balance the water.

Scaling or corrosive conditions can persist and cause problems to pool surfaces and equipment, even with the circulation system off. Water has a natural tendency to seek its own balance (and that could mean taking elements from its surroundings) and this does not stop during the winter months. Properly balanced water will provide better protection for pool equipment and surfaces during the off-season as well as during peak season.

(3) Prevent algae.

To help prevent algae growth over the winter months, a winter algaecide may be used. Be sure that the pool has been circulated adequately before shutting down so that the algaecide is properly dispersed. In warmer climates, a mid-winter application may be necessary.

(4) Prevent stains.

A sequestering agent (metal/scale treatment) applied to the water will help prevent any dissolved metals from staining the pool surface. Metals that may become insoluble during the off season are not being filtered as they would be in season. Sequestering agents will help hold the metals in solution and prevent staining. If a pool stains during the winter, it can be several months before it is treated. This would make the stain much more difficult to treat as fresh stains are always easier to remove. Sequestering agents can also help prevent the formation of scale, particularly in hard-water areas. Scale build-up on pool surfaces or equipment can lead to costly repairs.

(5) Clean.

Remove any dirt and debris from the water. Leaves, dirt and other unwanted debris can cause unsightly staining if left on pool surfaces for long periods of time. These stains will be more difficult to remove months later.

(6) Shut down equipment.

Be sure to turn off the equipment, including timers. Pumps can be damaged by running without proper water flow, so it is important to be sure that the timers are disabled so that the pump does not inadvertently start. Be sure to turn off lights as well. Because the light lenses will become hot with the bulbs on, contact with cold water can cause them to crack. Remove and store any equipment that may be damaged due to extreme weather conditions.

(7) Lower the water level and drain the lines and equipment.

Remove enough water from the pool so that the water level is at least below the skimmer. Water expands as it freezes, so be sure that water is removed from the lines or that antifreeze is added. Use non-toxic antifreeze that is appropriate for pools. Do not use automotive antifreeze. A shop-vac may be used to blow the water from the lines and then the lines can be plugged to ensure that pipes do not crack over the winter. Alternatively, the water may be drained below the lines in order to ensure that all water is removed from the plumbing. It is inadvisable to completely drain in-ground pools due to hydrostatic pressure from ground water in some areas. This can cause pools to crack or even pop out of the ground. Vinyl lined pools will wrinkle if completely drained and can be very time consuming and costly to repair. Pumps and other equipment should be completely drained by removing the drain plugs. All water should be removed from the filter to prevent damage to the filter housing. Be certain that there are no open valves that can leak water into the filter.

(8) Close access to the pool.

Swimming pools are a source a fun, recreation and healthy activity, but they can be a safety issue if not secured properly. This includes the winter months when the pool is not being used. Children may be curious about a closed pool and pools are less likely to be supervised over the winter, so it is important to be sure that children do not have access. When public or commercial pools are closed, they should be secured against public access altogether. A partially drained pool could constitute a significant fall hazard.

(9) Cover the pool.

Covering the pool can help to limit the amount of leaves, dirt and other debris that enter the pool over the course of the winter. Solid covers that fit securely will help minimize unwanted debris, rainwater or runoff from entering the pool. If a solid cover is used, some type of siphon should be employed to remove water and other debris that may accumulate on the cover throughout the winter. Keeping the water covered will make spring opening much easier as there will be less debris removal and less potential for issues such as algae and chlorine demand. Mesh safety covers will let rainwater through, but provide a convenient method to keep leaves and other debris from entering the pool.

(10) Store chemicals properly.

Pool products should be stored in a cool, dry, well-ventilated area separate from other products such as fertilizers, motor oil, grease, paint and other household and garden chemicals. Mixing these common items with certain pool products can lead to unwanted and potentially dangerous chemical reactions. Keep pool-care products tightly sealed in the original container to prevent contamination. Always store pool products where they are inaccessible to children and pets. It is best to discard test kit reagents and/or test strips at the end of the pool season. Testing materials have a shelf life, which declines rapidly once opened. Because accurate testing is so important to proper pool maintenance, it is best to start with new test reagents and/or test strips at the beginning of the next season.

The pool owner or operator should continue to check on the pool over the course of the winter. Rain or snow can raise the water level or cause the cover to sink. If this happens, then take action immediately to correct the situation. Check for any heavy debris that may have fallen into the pool or on the cover and remove it right away. Proper off-season care will lead to a much easier spring opening and a more enjoyable pool season.

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