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As the summer season comes to a close and fall begins to encroach, pool owners should start preparing to winterize the pool for the off-season, a big part of which involves selecting the right pool closing kit. Whether you’re winterizing an above-ground pool or you need an inground pool closing kit, the chemicals contained in these swimming pool closing kits are essential for the ongoing health of any pool system.
Using a pool winterizing kit not only helps to keep the pool clean and healthy during the winter season, but the pool closing supplies contained in these kits also make it easier to open the pool in the spring by reducing the risk of algae, staining, and damage to the pool and pool liner. Use this guide to find out what aspects to consider when selecting the best pool closing kit to winterize your pool before winter weather hits.
- BEST OVERALL: Doheny’s Master Pool Closing Kit
↓ Jump to Review - BEST BANG FOR THE BUCK: Rx Clear Winter Closing Kit
↓ Jump to Review - BEST CHLORINE-FREE: Robelle Premium Winter Pool Closing Kit
↓ Jump to Review - BEST CHLORINE-BASED: BioGuard Arctic Blue Winter Closing Kit
↓ Jump to Review - BEST FOR SMALL POOLS: In The Swim Pool Closing Kit
↓ Jump to Review
Our Top Picks
Browse our top picks for the best closing kit to ensure your pool is clean and protected during the off-season and ready to open in spring.
Best Overall
Doheny's Master Pool Closing Kit
Buy at Amazon Buy at Doheny's
What We Like
- Compatible with all pool types
- Available in a variety of sizes
- Contains time-released tablets for continuous protection
What We Don’t Like
- Individually purchasing chemicals may enable greater water compatibility
Specs
- Pool Size: Up to 35,000 gallons
- Pool Type: Suitable for above-ground, inground, salt, and chlorine pools
- Included Chemicals: Natural Chemistry Metal Free, Natural Chemistry Pool Magic Spring & Fall + Phos Free, Doheny’s Oxidizing Shock, and Winter Oxidizing Tablets
Winterizing the pool is an essential step to ensuring the ongoing health and protection of the pool system during the off-season, and Doheny’s Master Pool Closing Kit makes this process simple with a complete winterizing instruction guide. The pool closing kit is available in various sizes, making it suitable for pools from 7,500 gallons to 35,000 gallons. If your pool is larger than 35,000 gallons, you can simply purchase an additional kit and follow the instructions for proper chemical distribution.
This pool closing kit is a chlorine-free solution that is ideal for saltwater pools, though it can be used in above-ground, inground, salt, or chlorine pools with reliable results. Pool owners who invest in this kit will get a variety of pool closing chemicals, including slow-release winter oxidizing tablets that keep the pool protected for the entire off-season, as well as the oxidizing shock formula that kills bacteria, viruses, algae, and other contaminants, making this pool closing kit an excellent option for winterizing the pool.
Get the Doheny’s Master Pool Closing Kit at Amazon or Doheny’s.
Best Bang for the Buck
Rx Clear Winter Closing Kit
Buy at Amazon Buy at PoolSupplies.com
What We Like
- Compatible with all pool types
- Prevents algae growth and corrosion
- Works throughout off-season for easier spring opening
- Available in a variety of sizes
What We Don’t Like
- Chlorine-based formula may not be suitable for everyone
Specs
- Pool Size: Up to 45,000 gallons
- Pool Type: Suitable for above-ground, inground, salt, and chlorine pools
- Included Chemicals: Alkaplus pH Powder, All-in-One Shock X-Tra, and Winterizing Powder
While some pool closing kits charge extra for additional chemicals that aren’t strictly necessary for most pools, the Rx Clear Winter Closing Kit offers the essentials for pool winterization at a reasonable price. The pool closing kit comes with pH powder to help maintain the pH level of the pool, shock treatment to kill any algae, viruses, bacteria, or other contaminants, and a winterizing powder that works to protect the pool all winter long.
Pool owners can choose from several different kit sizes, ranging from just 10,000 gallons for smaller pools to 45,000 gallons for larger pools. It is important to note that while the chlorine-based formula is incredibly effective at eliminating contaminants and can be used in saltwater pools, it may not be the best choice for a saltwater pool system since these pools produce their own chlorine, and the addition of a chlorine-based chemical may unintentionally throw off the pool chemistry if not properly monitored.
Best Chlorine-Free
Robelle Premium Winter Pool Closing Kit
Buy at Amazon Buy at The Home Depot
What We Like
- Compatible with all pool types
- Chlorine-free formula is ideal for saltwater pools
- Removes and controls scale, stains, and discoloration
- Two different sizes available
What We Don’t Like
- Chlorine-free formula may not kill algae as effectively
Specs
- Pool Size: Up to 30,000 gallons
- Pool Type: Suitable for above-ground, inground, salt, and chlorine pools
- Included Chemicals: Robelle Winterizer, Robelle Winter Shock, and Robelle Anti-Stain Control.
The Robelle Premium Winter Pool Closing Kit is a chlorine-free product that is well suited for saltwater pools and isn’t as harsh on pool liners, pool walls, or pool equipment, making it an excellent choice for pools that don’t suffer from extreme algae buildup or bacterial contamination. Pool owners can choose between a 10,000, 15,000, or 30,000-gallon kit depending on the size of their pool.
The kit comes with a winter shock formula to kill viruses, bacteria, algae, and other contaminants before adding the winterizer and anti-stain control chemicals to protect the pool during the winter and maintain the health of the pool system. The anti-stain control formula will even remove existing scale, stains, and discoloration, instead of simply protecting the pool from future problems, making this chlorine-free option an excellent choice for pools that may not have been properly protected in the past.
Get the Robelle Premium pool closing kit at Amazon or The Home Depot.
Best Chlorine-Based
BioGuard Arctic Blue Winter Closing Kit
Buy at Walmart Buy at Hydro Pool
What We Like
- Compatible with all pool types
- Chlorine-based formula highly effective against bacteria, viruses, algae
- Long-lasting protection during the off-season
- Easy-to-use solution
What We Don’t Like
- Chlorine-based formula may not be suitable for everyone
Specs
- Pool Size: Up to 12,000 gallons
- Pool Type: Suitable for above-ground, inground, salt, and chlorine pools
- Included Chemicals: BioGuard Arctic Blue Algae Protector, BioGuard Arctic Blue Winter Shock
When a pool tends to have significant algae problems, or when it’s at risk of contamination from bacteria, viruses, and other contaminants, opting for the BioGuard Arctic Blue Winter Closing Kit is a great choice, largely thanks to its chlorine-based formula. The chlorine-based winter shock is a quick-dissolving, non-clouding product that oxidizes organic wastes and kills any contaminants quickly while preventing contaminant growth during the offseason.
After shocking the water, pool owners can then use the winter algae protector to prevent and control algae with a formula that is specifically designed to withstand the cold temperatures. If pool owners notice that algae seems to be appearing midway through the offseason, they can simply use the second included bottle of winter shock to kill off any contaminants and keep the pool protected through to the spring.
Get the BioGuard Arctic Blue Winter Closing Kit at Walmart or Hydro Pool.
Best for Small Pools
In The Swim Pool Closing Kit
Buy at Amazon Buy at In the Swim
What We Like
- Compatible with all pool types
- Contains slow-release oxidizing pool floater
- Wide variety of chemicals and pool protection supplies
What We Don’t Like
- Chlorine-free formula may not kill algae as effectively
Specs
- Pool Size: Up to 7,500 gallons
- Pool Type: Suitable for above-ground, inground, salt, and chlorine pools
- Included Chemicals: Pool Winterizing Inhibitor, Pool Winter Stain-Away, Chlorine-free winter pool shock, Winter Pool Floater (“non-chlorine” winter oxidizer), Winter SorbTM (oil absorbent winter chemical sponge)
Small pools can be just as effective as large ones for cooling off during the warm summer months, but it’s equally important to winterize them properly to prevent contamination and long-term damage. The In The Swim Pool Closing Kit comes with a chlorine-free pool shock to eliminate algae and other contaminants, as well as a stain-away product to remove existing stains and protect the pool walls, liner, and equipment from stains during the off-season.
Pool owners who invest in this kit also get the winterizing inhibitor to keep the pool protected throughout the winter season, a winter pool floater with a slow-release winter oxidizer, and an absorbing sponge, which absorbs lotions, oils, and scum to help keep the pool cleaner and free of waterline buildup and staining.
Get the In The Swim Pool Closing Kit at Amazon or In The Swim.
Jump to Our Top Picks
How We Chose the Best Pool Closing Kits
When putting together this list of the top closing kits for swimming pool winterization, it was necessary to consider a wide range of chemical treatments, pool closing supplies, and even how these chemicals interacted with certain pool winterizing covers (such as mesh covers) to find the best option for each category.
During the selection process, we considered the type and size of pool that each swimming pool winter closing kit was designed for. We then selected products in a variety of sizes that did not have a limitation on the type of pool they could be used to protect.
We also took into consideration the included treatments and pool supplies, as well as any additional features that could improve pool cleanliness and protection. Additionally, we made a distinction between chlorine-based and chlorine-free winterizing chemicals for pool protection since chlorine-free chemicals tend to work best for saltwater pools, while chlorine-based chemicals are highly effective for killing bacteria, viruses, and algae. We then used this information to assemble this list of the best pool closing kits for winterizing your pool.
What to Consider When Choosing a Pool Closing Kit
The size and type of pool can have a significant impact when choosing the right pool closing kit. Similarly, it’s essential to consider the treatments included in each kit and how they will interact with your existing water chemistry, while keeping in mind the typical winter conditions the pool will need to endure. Consider these key factors when choosing a pool closing kit.
Pool Type and Size
When shopping for a pool closing kit, begin by considering the type of pool you have. Typically, an above-ground pool winterizer will work on an inground pool, but depending on the type of liner or walls the pool has, you may need to opt for a kit that is specifically designed to work effectively with the liner or pool wall material.
Additionally, while chlorine-based pool closing kits can work in both chlorine and saltwater pools, it’s generally better to use a chlorine-free pool closing kit for a saltwater pool, since these pools generate their own chlorine.
After finding a product that is suitable for the pool type, you need to consider the size of the pool. We consulted with Donna Wilson, the manager of Carlton Pools in Trexlertown, Pennsylvania, who gave us some valuable insight: “The most important factor is your pool’s water capacity. Kits are sized by gallon range (e.g., 15,000, 30,000, or 40,000 gallons). Using a kit meant for a smaller pool won’t provide enough protection, while one for a much larger pool could be overkill,” she said.
Included Chemicals
When closing a pool, you may notice that kits often include a variety of chemicals, and these can vary from one kit to the next. “When choosing a pool closing kit, the first thing to check is what’s included. Most kits come with three essentials: a winter floater, algaecide, and a stain inhibitor. The quality of these chemicals is key. For example, non-chlorine floaters last longer under the cover compared to chlorine-based ones, which tend to dissipate too quickly,” explains Wilson.
Alongside algaecide for pool closing and winterization, you may also find a chlorine-based or chlorine-free shock chemical that is used to sanitize the water before closing. Some kits will also include a pH balancer to maintain proper pH levels while preventing equipment corrosion and damage, while a stain and scale preventer is similar to a stain inhibitor, but can also help to prevent calcium or metal deposits from sticking to the pool walls or liner.
Water Compatibility
If you simply pick a pool closing kit at random and dump the chemicals into the pool without regard for the water compatibility, it can significantly damage the pool. “This is often overlooked, but your pool’s existing water chemistry matters,” notes Wilson. Ideally, test the water before adding any closing chemicals to determine the pH, alkalinity, and calcium hardness.
Also consider any specific problems your pool may have, like high iron, high copper, or a high frequency of algae growth, and choose a closing kit that targets those concerns. Depending on the current water chemistry of your swimming pool, it may be more advisable to purchase chemicals individually rather than opting for a prepacked kit that is for more general-purpose use.
Regional Winter Conditions
Along with the pool water compatibility, pool owners should also consider the typical winter conditions that pools in their region must endure during the off-season. Wilson mentions that “climate plays a big role. In areas with frequent freeze-thaw cycles, we recommend adding a second dose of algaecide mid-winter.”
Depending on the severity of the winter, you may also want to invest in a pool closing kit that comes with winterizing chemicals and antifreeze for any plumbing lines. On top of that, consider purchasing a proper pool cover for the freezing weather. In regions with milder winters, less intensive treatments can be just as effective, though an appropriate pool cover is still appropriate rather than keeping the solar pool cover most people use during the summer.
Additional Features
Basic pool closing kits will only include the chemicals required to prepare and protect the pool for the winter, but larger pool closing kits may include a variety of extras that can make pool protection easier.
- Enzymes can be used to help break down organic matter that is trapped in the pool, like oil, lotions, and dirt.
- Time-release floaters provide continuous chemical distribution during the off-season, similar to floaters used with chlorine tablets.
- Absorbing sponges are used to absorb oils and scum throughout the winter months to minimize the risk of developing waterline staining and buildup.
- Air pillows are designed to protect the walls and liner of the pool by creating a barrier against the expansion of ice during freezing weather.
- Phosphate removers are intended to reduce food sources for algae, though they may not be necessary for all pools. “Some kits come with a phosphate remover, which is really a must-have for mesh-covered pools. Since mesh lets rain and debris through, phosphates can build up and feed algae over the winter,” says Wilson.
Tips for Using Pool Closing Kits
Generally, a pool closing kit will come with detailed instructions on how and when to use each chemical included in the kit, but before you start adding anything to the pool, you should take the time to properly clean the pool and balance the existing water pH and chlorine levels. This will help ensure that you don’t throw off the water chemistry when you begin the pool closing process.
Next, you should shock the pool to sanitize the water and kill any algae or other contaminants, then add the other chemicals as necessary, including algaecide, stain and scale control, and winterizing chemicals. Once the chemicals have been added, run the pump for several hours to give the chemicals a chance to circulate through the pool water and pool system.
Clean the filter thoroughly, plug the pipes, and remove any water from the hoses to prevent freezing. Then, clean and store the pumps, filters, and other equipment indoors before covering the pool with a suitable cover for the winter. During the winter, check the pool regularly for any signs of algae growth, and add more algaecide if necessary.
- Clean the pool and balance the pool chemistry before using a pool closing kit.
- Run the pump for several hours after adding chemicals for proper distribution.
- Monitor the pool throughout the winter and add more algaecide if necessary.
FAQs
Properly cleaning, preparing, and protecting the pool is crucial in preventing long-term problems and off-season damage. That’s why it’s necessary to use appropriate pool closing chemicals to winterize the pool. However, before picking up the first pool closing kit you see, it’s important to have an understanding of what your pool needs and how a pool closing kit can help. With this in mind, check out these answers to some of the most frequently asked questions about pool closing kits.
As long as the pool doesn’t have any specific problems or custom requirements, most pool closing kits are a convenient solution that come with the chemicals necessary to effectively winterize and protect the pool, making them well worth the investment, especially when you consider that the cost of the individual products is lower when bundled together in a kit.
Expect to pay about $25 to $100, depending on the size of the kit and the variety of chemicals included in the kit. Keep in mind that the larger the pool, the more chemicals you will require, leading to higher pool closing kit prices.
Measure the length, width, and average depth of your pool, or the diameter and depth for circular pools, then use these measurements to find the volume of your pool. Once you know the volume of the pool, you can determine what size pool closing kit you need. Wilson notes that “most kits are labeled by gallon capacity (e.g., 15,000, 30,000, or 40,000 gallons). Just pick the one that matches your pool’s size for proper protection.”
In order to handle the fluctuations in pool pH and chlorine levels over the winter, it’s typically recommended to use a 30 percent polyquat or a 60 percent polyquat algaecide, since these products are highly effective in cold temperatures.
It is recommended to shock the pool before closing it for the winter, though you can choose to use a chlorine-based or chlorine-free pool shock solution depending on the type of pool and personal preference. Chlorine-based shock is stronger and more effective at eliminating bacteria, viruses, algae, and other contaminants, but chlorine-free shock is equally tough on the liner, walls, and pool equipment.
