A comprehensive guide to late season pool care

by arslan_ahmed | November 2, 2023 3:06 pm

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By Emily Johnson

The summer season is the time for communities to seek out the swimming pool. From Victoria Day through Labour Day (and sometimes beyond), pools are filled with people splashing, swimming, and playing during which bather loads get heavy and outside temperatures rise.

Maintaining pool water in top condition demands continuous effort throughout the entire season, not just during openings and closings. As the season progresses, various factors can lead to water quality issues that may not have been evident when the pool was first opened.

To effectively prevent unsightly conditions and potential hazards to swimmers’ health, pool operators and technicians should consider a few essential factors when tailoring their recommendations. By diligently adhering to pool maintenance routines, the water can remain clean and safe not only throughout the entire duration of summer vacation, but also well into the fall.

Keeping the water clean and sanitized

Establishing an effective routine for pool maintenance involves prioritizing the sanitization of water to eliminate harmful organisms. While chlorine is effective in killing most biological contaminants, relying solely on it may not address all types of pollutants. As the demand for pool chemicals grows, exploring alternative methods can contribute to maintaining the water in its desired condition.

Complementary solutions: Chemicals in harmony

To enhance the effectiveness of free chlorine and protect it from rapid depletion due to direct ultraviolet (UV) light exposure, pool owners can add stabilizer in the form of cyanuric acid (CYA). Trichlor-based tablets can also slow down tablet dissolution, and certain varieties may contain additional components that offer benefits like clarification or scale inhibition. Further, supplemental chemicals can assist in eliminating unwanted contaminants, complementing chlorine’s primary role in targeting biological organisms.

Regular oxidation routine

Rain, source water, swimmers, thunderstorms, and nearby vegetation introduce waste products that must be eliminated from the pool. While some pool operators only use oxidizers to address significant issues like algae outbreaks or cloudy water, a more economically viable approach is to perform weekly shocks for oxidation to maintain a clean pool.

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During oxidation, electrons are transferred between hypochlorous acid and its target. Nitrogen and various nitrogenous compounds are common targets for chlorine as they readily react with it. To prevent these nitrogenous compounds from continuing to react with the free chlorine necessary for proper sanitization, a weekly shock can be administered for regular maintenance. Shocking the pool after rainstorms or heavy use also proves effective. Additionally, promptly removing visible debris like leaves, pine straw, or tree limbs can prevent major issues and chlorine depletion. Utilizing regular maintenance shocks to prevent contaminant accumulation will help avoid costly battles with super-chlorination or water dilution.

Water balance: pH and chlorine equilibrium

Maintaining balanced water is crucial not only for safeguarding pool surfaces and equipment but also for optimizing chlorine’s effectiveness. When chlorine is added to the water, it breaks down into hypochlorous acid (HOCl) and hypochlorite (OCl-). HOCl, which is essential for sanitization and oxidation, performs most efficiently in neutral environments with a pH range of 7.4 to 7.6.

HOCl ß à H⁺ + OCl^–

A lower pH in the water favours the production of more HOCl, while a pH above 7.6 shifts the equilibrium towards generating more OCl-, which is significantly less effective—about 80 to 100 times weaker in its sanitizing capabilities. OCl-’s weaker negative charge repels negatively charged micro-organisms, leading to less effective elimination. When choosing a chlorine form, such as trichlor, calcium hypochlorite (Ca[ClO]₂), liquid chlorine, or saline, it is crucial to consider their varying impacts on the water’s pH.

pH	% HOCl	% OCl–
7	76	24
7.2	66	34
7.5	50	50
7.8	33	67
8	24	76

Alkalinity effects on sanitization

Maintaining the proper total alkalinity (TA) range is crucial for ensuring a balanced pH level. If the TA falls below 40 parts per million (ppm), it can lead to pH fluctuations that are challenging to correct. Low TA levels can cause the pH to decrease, negatively affecting swimmers’ comfort and causing damage to pool surfaces and equipment.

The impact on alkalinity becomes significant when considering chlorine-based sanitization methods. Both salt chlorinators and sodium hypochlorite introduce a byproduct called sodium hydroxide (NaOH). If not appropriately balanced with acid, this can create a more alkaline environment, leading to issues like cloudy water or conditions that promote harmful scale formation.

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On the other hand, the use of trichlor as a sanitizer over time can reduce TA due to the quantity applied and the pH balance of the water source and rainwater. To ensure a well-balanced pH level between 7.2 and 7.6, it is essential to measure TA weekly and maintain it within the range of 80 to 150 ppm.

Influence of water temperature on sanitizer and water balance

The water temperature is a critical non-chemical factor to consider, especially during extreme conditions. It plays a significant role in calculating the Langelier Saturation Index (LSI) and affects chlorine’s ability to control bacteria, algae, and other micro-organisms. The overall water balance evaluation involves taking into account temperature, water hardness, TA, pH, and total dissolved solids (TDS). Higher temperatures tend to promote scaling conditions, while lower temperatures can create corrosive conditions.

During the first half of the season, warmer water combined with high TA and calcium hardness can cause calcium to precipitate out of the solution and form scale deposits. Scale is not only unsightly and difficult to remove, but it can also cause problems for pool equipment. In the case of a chlorine-generator, scale formation on the electrolytic cell can lead to reduced performance and a shorter lifespan. Regular cleaning of the cell with an acidic solution is necessary to remove any hard deposits, and adding a calcium sequestering agent monthly can help prevent scale formation, especially in pools with higher TA levels.

Warm water also has a significant impact on chlorine effectiveness. Chlorine degrades more rapidly in warmer conditions, especially if there is not enough stabilizer present to protect it from UV sunlight. During the warm months of June and July, water temperatures can exceed the usual 25 to 27 C (78 to 82 F) range in some places. This can lead to faster dissolution of slow-dissolving chlorine tablets, requiring more frequent replacements if the free chlorine residual is not maintained. Additionally, the warm and wet environment provides a comfortable breeding ground for organisms, which increases the workload for free chlorine.

Tailoring enzyme packages for different pool environments

Bather waste containing proteins, starches, oils, and greases can pose challenges for chlorine to break down effectively. While chlorine can oxidize and break down most of these waste products, it also gets consumed in the process, leading to reduced effectiveness in killing bacteria. Incorporating supplemental compounds with enzymes can alleviate this burden on chlorine, enabling it to concentrate on eliminating harmful bacteria and nitrogenous compounds more efficiently. Selecting the appropriate enzyme package during new product development is a critical and intricate process to optimize performance. The choice of enzymes should be based on the specific environment where the product will be used and the type of organic materials it aims to remove. Enzymes can be naturally occurring through controlled biological processes or produced synthetically. Regardless of their origin, enzymes exhibit high selectivity and only target specific structures. This selectivity is a result of the relationship between the target’s shape, the substrate, and the active site where the reaction takes place. The active sites are uniquely shaped to fit and merge with specific substrates, much like pieces of a puzzle. Pool products offering a broad range of enzymes tend to be more effective than those containing only one or two types. The types of waste present in pools may differ from those found in spas. Therefore, the enzymes chosen for pool products should address a variety of waste sources, including those from biological or environmental origins. For example, amylases can break down starches released during the degradation of algae or leaf debris, while proteases help break down waste from animals or swimmers. Conversely, the enzyme package used for pools might be ineffective when used in spas. In spas, waste matter often comes from biological sources, and enzymes like lipase or mannanase are needed to target fatty and oily residues left behind from lotions, hair products, or body oils, which tend to accumulate due to the warmer water temperature. Further, the enzyme packages used in commercial pools and spas would differ from those used in recreational pools. Commercial pool operators frequently use automatic feeders to provide continuous, metered doses of enzymes. This supplementation helps avoid inconvenient pool downtime, which is often accompanied by high chlorine residuals after a remediation treatment.  Pool owners and service technicians should implement a weekly algicide prevention routine. Stopping it from growing is always preferred to having to treat it.

 

Regularly testing measurable free chlorine levels is crucial, especially as more swimmers take advantage of the warmer water. If testing reveals a need for more chlorine, a booster shock may be necessary to break up combined chlorine, or adjustments to the chlorinator’s output may be required. It is essential to understand the pool’s behaviour, events, and the surrounding environment throughout the summer to make appropriate adjustments to the maintenance routine.

The warm and wet environment also encourages algae growth. Regularly brushing stagnant areas at least weekly is necessary, and using a maintenance algaecide weekly instead of biweekly should be considered. Quat-based algaecides can handle most types of algae, but in areas where more resistant types are common, polyquat or chelated copper-based algaecides would be better choices. The frequency and amount of free chlorine replenishment vary based on factors such as water circulation, filtration patterns, bather load, source water, and the natural surroundings.

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 Enhancing pool cleaning with clarifiers and enzymes

While sanitization is crucial for maintaining a clean pool, it should not be the sole focus. Ancillary chemicals such as clarifiers and enzymes play a significant role in breaking down non-living contaminants, saving chlorine’s energy for more effective tasks. Clarifiers assist in aggregating small particles into larger chains that the filter can capture. Despite proper filtration and chlorine use to remove visible contaminants, oils and dirt tend to accumulate along the waterline.

Enzymes, which are naturally-derived catalytic proteins, are valuable for breaking down organic matter into more manageable forms. Specific enzymes target nitrogenous amino acids, fats, or oils for efficient removal. Some products combine different types of enzymes to combat multiple types of contaminants. Enzyme technology is often incorporated with surfactants or phosphate removers.

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The synergistic relationship between enzymes and surfactants enhances the performance of dual-action ancillary maintenance products. Surfactants attach their hydrophobic “tail” to oils at the surface, while the hydrophilic “head” lifts oils from the surface, allowing them to be broken down and removed through filtration. Surfactants also help prevent oily buildup in the filter. Additionally, phosphate removal products not only prevent calcium phosphate precipitation but also contribute to the clarification process. By eliminating these oxidizable non-living wastes, the demand on chlorine is reduced, leading to overall improved water quality.

Ensuring a sparkling finish

Each pool exhibits distinct behaviours and characteristics. By implementing a thoughtful maintenance strategy and remaining adaptable to make necessary adjustments, pool owners can overcome the late-season challenges they often encounter. Along with regularly monitoring the free chlorine levels, the use of complementary products will collaboratively contribute to keeping the pool enjoyable, clean, and tranquil for everyone until the end of summer, when children return to school, and, weather permitting, even into late fall.

Author

Emily Johnson, born and raised in South Carolina, graduated with a bachelor of science degree in biological sciences and chemistry minor from the University of South Carolina. She is a recreational water enthusiast living in Atlanta, Ga., with her two rescue dogs who love a good dip in a splasher pool. She has been working for research and development at BioLab Inc., a KIK Custom Products Company, since 2014. She can be reached via email at emily.johnson@biolabinc.com.

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