A beginner’s guide to saltwater pool troubleshooting

by jason_cramp | April 13, 2020 8:15 am

By Alicia Stephens

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To understand saltwater pool chemistry, one must start by trying to identify the facts from fiction. Many misconceptions stem from a lack of knowledge around the chemistry of saltwater pools. The most common misunderstanding about such pool types is that they are fundamentally different and do not use chlorine as a sanitizer. In reality, saltwater pools use a special process to create free available chlorine, but require similar products to maintain water quality.

Saltwater pools experience many of the same problems that befall traditional pools, which use chlorine as the primary sanitizer. That said, there are some attributes that require attention in all saltwater pools, especially due to the unique way the sanitizer is produced. This includes balancing the pH, maintaining chlorine residual, battling algae, and preventing scale. Each one of these potential issues can be frustrating for a pool owner, but they can be prevented with proper maintenance.

Maintaining pH levels

All aquatic professionals will agree pH is a key water-balance parameter. In the process of generating chlorine in saltwater pools, pH in the water increases over time. This is a result of the byproducts created in the process of turning salt into free available chlorine. Sodium hydroxide, which has a pH of 13.5, is produced in excess. This byproduct of electrolytic chlorine generation is responsible for the steady increase in pH experienced by saltwater pools.

As a result, these pool types require routine pH adjustment; therefore, it is important to add a pH decreaser to the water on a weekly basis when using a chlorine generator. Without the product, the pH may continue to rise in the pool. If left unchecked, high pH levels can lead to multiple problems, including ineffective sanitizer, cloudy water, scaling, and algae.

Another issue saltwater pools may experience during peak season is failure to maintain a free chlorine residual. This is also a common problem in traditional halogen pools, but in saltwater pools the problem can typically be tracked down to one of two causes—either the pool is experiencing a chlorine demand, or the cell is no longer physically capable of producing enough free chlorine.

Meeting a chlorine demand

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Chlorine demand is a problem faced by many pools that use the chemical as the sanitizer of choice. A chlorine demand is present when the pool shows the consistent inability to establish a sanitizer residual. This occurs when there are too many contaminants consuming the chlorine and not enough sanitizer in the water to oxidize these pollutants. Pools in a demand have no sanitizer available for bather protection. The chlorine generator cell often cannot make chlorine quickly enough to provide the amount needed to overcome the demand. If the need is large, an additional source of chlorine is required to break the demand and re-establish the sanitizer level.

There are times when the pool may not be in a chlorine demand, but it still may not be able to maintain a free chlorine residual. Common causes for this include:

Not running the cell generator long enough

As the electrolytic cell only generates chlorine while the pump is running, ensuring the equipment operates for the required amount of time is critical.

An undersized cell

Using a cell that is too small for the pool can also result in low chlorine residual. An undersized cell may not be able to produce enough sanitizer to maintain 1 to 4 parts per million (ppm) chlorine residual, even with ample pump run time and setting the cell for maximum output.

Scale accumulation on the cell plates

Scale deposits can also impact how well an electrolytic cell produces chlorine. Buildups are more likely to occur as the pH of a saltwater pool increases. Once the scale accumulation is substantial, it will reduce the ability of the cell plates to pass electricity through them. Electricity, generated through electrolysis, is the key to chlorine production. The higher the scale buildup, the less chlorine is produced.

There are two types of calcium scale formations: calcium carbonate and calcium phosphate. Each accumulation is influenced by different factors. Calcium carbonate is the most common type of scale found within any pool environment and makes up the majority of buildups found on chlorine generator cell plates. These scale formations are influenced by three main factors: water temperature, pH, and concentration.

On the other hand, several water-balance parameters lead to the formation of calcium phosphate. That said, this scale buildup is not driven by high pH. However, higher concentrations of both calcium and phosphate in the pool will cause increased risk of scale formation.

It is imperative to use a scale inhibitor product to help prevent buildups in chlorine generator pools. In addition, some manufacturers warn against high phosphate levels to prevent the small amount of calcium phosphate scale that may form in the chlorine generator. Adding a phosphate remover into the pool maintenance routine can help reduce problem-causing phosphate-based scale and improve cell efficiency.

Improper salt levels

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In addition to cell run time, size, and scaling, there are other parameters that can affect the production of chlorine in a saltwater pool. Improper salt levels can cause damage to the cell, as well as inhibit the production of chlorine. Many pool owners often make the mistake of thinking that when chlorine levels are low, simply adding more salt will fix the issue. This may not always hold true. Many pools with the correct salt level may experience low chlorine residuals due to other reasons.

Life condition of the cell

Finally, the cell’s age can also impact chlorine residuals. The electrolytic plates in the cell are coated with a metal called ruthenium. This chemical element is necessary for electrolysis and generating chlorine. As the metal coating wears away with time, the cell’s ability to generate chlorine also decreases. Often, lack of chlorine is due to an aged cell that should be replaced.

Algae growth

One of the most common issues seen in saltwater pools—similar to traditional chlorine pools—is algae. Maintaining a proper free chlorine residual and pH balance is key because many saltwater pool owners choose not to add a preventative algaecide as part of their routine maintenance plan.  High pH reduces the effectiveness of chlorine and provides a carbon dioxide rich environment, which can lead to the increased probability of algae growth.

In addition, all of the previous causes of low chlorine residual can contribute to a higher chance of getting an algae bloom in a saltwater pool. Most algaecides are compatible with saltwater pools and should be incorporated into maintenance routines or when troubleshooting algae problems.

Conclusion

Saltwater pools provide a premium experience to pool owners. However, a proper maintenance routine must be followed to prevent problems—the same issues often found in traditional chlorine pools that are resolved by similar activities. That said, some of the problems are exclusive to saltwater pools and require specific products or actions to fix them. The ultimate goal is to provide all pool owners with clear, pristine water, and saltwater pools are no different.

[4]Alicia Stephens is the education and training manager for Biolab Inc. In her 19 years with the company, she has focused primarily on education, training, and development, as well as technical support and new product research and integration. Currently, Stephens supports all education and training initiatives for the Biolab Pro Dealer division. She can be reached via email at alicia.stephens@biolabinc.com[5].

Source URL: https://www.poolspamarketing.com/trade/beginner-guide-saltwater-pool-chemistry/

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