Essential Pool Closing Chemicals and Their Uses

Closing your pool can seem like a big task as summer ends. The right pool closing chemicals make this easier though. Winterizing your pool requires specific chemicals to protect it during colder months. 

The chemicals are pH and alkalinity adjusters, chlorine or non-chlorine shock, stain and scale preventer, phosphate remover, algaecide, winterizing floater, and pool antifreeze. These products help prevent algae growth and other issues that can arise in winter.

pH and Alkalinity Adjuster

pH and alkalinity adjusters are crucial for maintaining balanced pool water chemistry. Properly balanced pH (7.4-7.6) and alkalinity (80-120 ppm) prevent issues such as corrosion, scaling, and irritation to swimmers’ eyes and skin. These adjusters help stabilize the water, ensuring that other chemicals work effectively.

Using pH and alkalinity adjusters during pool closing helps protect your pool surfaces and equipment from damage over the winter months. They also make spring opening easier, reducing the need for extensive chemical treatments.

Choosing the Right pH and Alkalinity Adjuster

Pool Surface Type

For concrete or fiberglass pools, use a pH increaser (sodium carbonate) or alkalinity increaser (sodium bicarbonate) to maintain proper levels, preventing etching or surface damage.

Vinyl and fiberglass pools are less prone to chemical damage but still require balanced pH and alkalinity to avoid liner wrinkles or discoloration.

Pool Water Chemistry

If your pool tends to have high pH or alkalinity, use a pH decreaser (sodium bisulfate) or muriatic acid to bring levels down.

To raise low levels, use a pH increaser or alkalinity increaser. Ensure gradual adjustments to avoid overcorrection.

Chlorine or Non-Chlorine Shock (Oxidizer)

Shocking your pool is a vital step in maintaining water clarity and sanitation, especially when closing your pool for the season. There are two main types of shock treatments: chlorine shock and non-chlorine shock (oxidizer). Each serves to eliminate contaminants and ensure the pool water remains clean throughout the winter months.

Chlorine Shock

Chlorine shock, also known as calcium hypochlorite, is a powerful sanitizer that increases chlorine levels in the pool. It’s particularly effective at killing bacteria and algae, ensuring that your pool water remains sanitized and free of harmful microorganisms throughout the winter. 

Chlorine shock is suitable for all pool surfaces, including vinyl, fiberglass, and plaster, but it’s essential to allow it to dissolve fully to prevent potential surface bleaching or damage.

Non-Chlorine Shock (Oxidizer)

Oxidizer plays a vital role in pool maintenance. This chemical helps clear cloudy water and remove organic contaminants without raising chlorine levels.

When winterizing your pool, using oxidizer can be an important part of the process to keep your pool water clean and clear throughout the off-season without increasing chlorine levels.

Oxidizer is safe for all surfaces, including concrete and plaster. It prevents the harsh effects of chlorine on these surfaces, which is particularly beneficial during the long winter months when the pool is not in use.

Stain and Scale Preventer

Stain and scale preventer protects your pool from unsightly stains and buildup by keeping minerals and metals in your water from forming deposits on surfaces. Using it is essential for all types of pools, including inground, above ground, and saltwater pools. Add the stain and scale preventer to the water after shocking, once chlorine levels have dropped to normal (1-3 ppm).

Choosing the Right Stain and Scale Preventer

Pool Surface Type

Concrete or plaster pools are more prone to staining and scaling due to their porous nature. Choose a stain and scale preventer that is specifically formulated for hard surfaces, ensuring it effectively prevents mineral buildup and staining.

For vinyl or fiberglass pools, use a product that is safe for these non-porous surfaces. Some preventers are designed to be gentle on vinyl and fiberglass while still providing effective protection against scale and stains.

Water Chemistry

If your pool has high calcium levels, you’re more likely to experience scaling. Choose a stain and scale preventer that specifically targets calcium deposits, helping to prevent them from adhering to pool surfaces.

If your water source has high levels of metals like iron, copper, or manganese, look for a stain preventer that chelates (binds) metals, keeping them in solution and preventing stains.

Phosphate Removers

Using phosphate removers as part of your pool winterization process can be an effective strategy to prevent algae growth during the off-season. Phosphates are a primary food source for algae, so removing them before closing your pool can help keep the water clear and algae-free until spring. 

Before closing your pool, test the water for phosphate levels. If phosphates are present, apply the recommended dose of phosphate remover according to the product instructions, typically after the stain and scale preventer has circulated.

Choosing the Right Phosphate Remover

Before selecting a phosphate remover, test your pool water to determine the phosphate levels. You can use a phosphate test kit or strips. Knowing the concentration of phosphates will help you choose a product with the appropriate strength.

If your pool has high phosphate levels (above 1,000 ppb), choose a high-strength product which is designed to handle large amounts of phosphates efficiently.

For phosphate levels below 1,000 ppb, most products are usually sufficient. These are often used for both maintenance and winterization.

After treating the pool with a phosphate remover, consider using a chlorine-free shock to oxidize any remaining organic contaminants.

Winter Algaecide

Algaecide prevents algae growth during the cold months. It works effectively to stop algae from blooming in pools, remaining active for several months and keeping the water clear and clean until spring. It’s an essential as part of most pool owners’ winterization kits.

Adding winter algaecide ensures pool sanitation is in check and reduces the need for extensive cleaning when reopening the pool. Always follow the manufacturer’s instructions for proper use.

Choosing the Right Winter Algaecide

Pool Surface Type

For concrete or plaster pools, use a non-metallic algaecide, such as polyquats. These are less likely to stain or damage the surface.

For vinyl or fiberglass pools, avoid algaecides with high copper content, as they can cause staining. Look for non-staining formulations, such as polyquats or copper-based algaecides specifically designed for these surfaces.

Pool Water Chemistry

If your pool’s pH tends to run high, avoid copper-based algaecides as they can cause staining. Opt for polyquat algaecides, which are effective across a wide pH range.

High calcium levels can cause scaling, so avoid products that might contribute to this. Polyquats are a safer option here as well.

Climate Considerations

In milder climates where the pool water may not get very cold, a lower concentration of algaecide might suffice.

For pools in regions with harsh winters, consider using a stronger, long-lasting algaecide, such as a 60% polyquat, to ensure effectiveness throughout the season.

Pool Usage

For saltwater pools, choose an algaecide that is compatible with salt systems. Avoid high copper content products as they can interfere with the salt chlorine generator.

Heated pools that remain open longer may require additional treatments or stronger algaecides since algae can grow more easily in warmer water.

Algae Type

Most standard algaecides will work against green algae. Polyquats and copper-based algaecides are both effective.

For more stubborn types of algae like mustard algae or black algae, you’re going to need specific algaecide designed to target those types, often containing higher concentrations of active ingredients.

Make sure to follow the manufacturer’s instructions on dosage and application to get the best results from your chosen algaecide.

Winterizing Floater

Winterizing floaters, also known as slow-release winter balls or winter pills help maintain clear water throughout the winter months. They work by releasing chemicals gradually, which prevents algae growth and keeps the pool clean.

Using these products alongside other pool maintenance chemicals ensures a hassle-free opening in spring, as it simplifies pool care and reduces the need for frequent water treatments.

Choose the right slow-release option based on your pool type. These winterizing supplies contain chemicals that stabilize the water and prevent stains. 

Choosing the Right Winterizing Floater

Pool Surface Type

If you have a concrete or plaster pool, opt for a winter ball or pill that doesn’t contain ingredients that could stain or etch the surface. Look for products that are safe for all pool surfaces.

If you have a vinyl or fiberglass pool, ensure the winter ball or pill is specifically labeled as safe for vinyl or fiberglass. Some products may contain chemicals that could cause discoloration on these surfaces.

Pool Size

For small to medium pools, one standard-sized winter pill or ball is usually sufficient. Check the product’s coverage area to ensure it matches your pool’s volume.

For large pools, you may need to use multiple pills or balls, or choose a larger, high-capacity product designed for extensive water volumes.

Pool Type

Most slow-release products are designed for inground pools. Ensure that the product is compatible with your specific pool system, especially if you have unique features like a saltwater system or an attached spa.

They also make winter pills or balls formulated for above-ground pools, as these often have different chemical needs due to their materials and structure.

Climate Considerations

If your pool experiences mild winters, a standard winter pill or ball with a lower concentration of chemicals might be sufficient to maintain water quality.

In colder climates where the pool will be closed for several months, a stronger, long-lasting winter ball or pill is recommended to ensure that it continues to release chemicals throughout the winter.

Pool Water Chemistry

For saltwater pools, choose a winter ball or pill that is labeled as safe for saltwater systems. Some products may specifically support saltwater pool chemistry.

If your pool tends to have high calcium levels, avoid products that could contribute to scaling. Look for pills or balls that help prevent scaling and buildup.

Features and Additives

Some winter balls and pills include algaecides to prevent algae growth. If algae is a common issue, choose a product with this added feature.

If staining has been an issue in the past, select a winter pill or ball that includes stain prevention chemicals.

There’s even products with built-in clarifiers that can help keep the water clear and reduce the need for extra maintenance when opening the pool in the spring.

Pool Antifreeze

Pool antifreeze is an essential chemical for protecting your pool’s plumbing system during the winter months, especially in regions where temperatures drop below freezing. It prevents water in the pipes from freezing, expanding, and causing cracks or bursts that could lead to costly repairs. Unlike automotive antifreeze, pool antifreeze is non-toxic and specifically formulated for use in pools, ensuring it’s safe for both your plumbing and the environment.

Start by draining as much water as possible from your pool’s plumbing lines. Use a shop vac to blow out any remaining water from the lines to minimize the risk of freezing.

Next, pour the antifreeze directly into the pool lines through the skimmer or return jets. You can use a funnel or an antifreeze dispensing tool to make this easier and more accurate. The amount of antifreeze needed depends on the length and diameter of the pipes, but it’s generally recommended to use about 1 gallon of antifreeze per 10-15 feet of pipe.

After adding the antifreeze, seal the lines with winterizing plugs to keep the antifreeze in place and prevent water from entering the pipes during the winter.

Conclusion

Closing your pool for the winter can be straightforward with the right chemicals and preparation. By using products like pH and alkalinity adjusters, oxidizers, stain and scale preventers, algaecides, and winterizing floaters, you’ll protect your pool throughout the colder months and ensure an easier opening in spring.

You can find all the necessary pool closing chemicals at Carlton Pools. If you’d prefer to have your pool closing handled by trusted professionals, Carlton Pools offers several pool closing plans. Contact their service team to choose the best option for your pool, and enjoy peace of mind this winter.

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