The Corrosive Argument Against Saltwater Pools

Our stand towards saltwater pools can be summed up with a quick glance at salt’s symbol on the periodic table: “Na.”

There’s a longstanding idea in most of our minds that saltwater pools are the more natural and environmentally-friendly option. That idea, while widespread, is not only shortsighted but can sabotage your pool from the inside out.

At J Designs Pool and Spa, we have 15 years of experience building and renovating pools with many sanitation systems. We’ve grasped a holistic and honest view of the popular sanitation systems throughout our tenure.

We don’t want a saltwater sanitation system to deconstruct your pool’s structural integrity, so we will deconstruct the misguided favorable view surrounding these corrosive systems.

This article will outline the lesser-known problems with saltwater pools so that you can make an informed decision about which sanitation system is best for maintaining your dream pool.

SALTWATER POOLS AND UNBALANCED WATER

There’s a common misconception that saltwater sanitation systems are the golden alternative to the problems associated with chlorine systems. The reality of Salt Pools is that they are actually chlorine pools – yes, salt is sodium chloride.

The only difference with salt systems is that instead of adding chlorine to the water, you add salt. Then, the salt-chlorine generator converts salt to chlorine (more chemistry for the win)!

While homeowners naturally want beautiful and durable finishes in their pools, the look and durability of a good pool finish are highly dependent on its environment. Getting 20 to 25 years of use out of a pool finish requires diligent monitoring and proper water balance. That feat, however, is difficult with saltwater sanitation systems.

Pool finishes are thin coatings applied to the concrete shell of the pool. The lifespan of the pool finish is highly dependent on the water’s chemistry. Similar to most aspects of life, the best way to be set up for long-term success is by striking a balance. Extremes are detrimental, but even more so when it comes to pH since your pool finish is always underwater.

While maintaining balanced pool water is not always easy, pool professionals do have an ally to turn to: The Langelier Saturation Index (LSI). This index is a helpful tool for checking for factors like pH, alkalinity, calcium hardness, and temperature to give you a snapshot of your pool's overall health. This is particularly important for salt cells since these systems need regular monitoring to ensure they're working correctly and producing the right amount of chlorine.

“To assure proper generator function, maintaining the appropriate salt concentration is important for other reasons. Too much salt can increase the potential for corrosion and also make the water taste and feel more like seawater (salt residue on the skin after leaving the pool). On the other hand, too little salt can result in decreased cell efficiency (lower chlorine production) and shorter electrode life. Since most of the chlorine generated reverts back to chloride again during use, the salt is automatically recycled. As a result, salt will only have to be replaced after repeated backwashing, splash out or when partially draining and refilling,” says Aqua Magazine.

Translation: don’t be salty.

SALTWATER PREMATURELY ERODES THE POOL 

Saltwater pools, with a higher salt content than freshwater pools, can cause both surface-level and structural damage. It's important for potential pool owners to understand these risks and count the cost before taking the plunge.

Salt is an extremely stable compound… until it’s diluted, that is. To reduce the salt level to a safe range, you can either dilute the water or drain it completely.

When there is a high amount of salt in the pool water, it can affect the solubility of calcium carbonate. The pool will try to balance itself by taking calcium from the cement surface. This can make the pool finish rough and prone to damage. Additionally, the presence of "aggressive water" can allow elements like algae to attach to the plaster, causing unsightly stains on the pool finish.

The corrosive effects of saltwater go beyond the surface. Over time, the salt can erode the plaster finish and even penetrate the concrete shell of the pool, reaching the steel structure underneath. This can lead to more serious and costly damage, requiring extensive repairs.

This conundrum has sparked an ongoing debate among pool builders, plaster professionals, and equipment manufacturers. While there is no concerted effort to ban the brine, some merited hesitancy exists. The NPC (National Plasterers Council) and the ACI (American Concrete Institute) have adopted measures to avoid the use of salt in pools.

DRAINING A SALTWATER POOL IS DIFFICULT AND BAD FOR THE ENVIRONMENT

Draining a saltwater pool is not a walk in the park; the effort is akin to a steep climb up a mountain in Runyon Canyon Park. 

In the words of Elle Woods, “What? Like, it’s hard?”

Yes indeed.

Eco-conscious cities in Southern California have been spearheading the strict rules around discharging pool water into the storm drain. 

Saltwater pool waste can harm the freshwater aquatic environments by introducing too much salt to a freshwater system. As a result, cities like Oceanside mandate that you dechlorinate your pool water before draining it into the street.

In addition to harming freshwater ecosystems, saltwater from pools can also harm vegetation.

“Saltwater swimming pools and spas are prohibited and illegal to be drained to the storm drain system/street or sanitary sewer system. Local creeks and rivers are very sensitive to salt concentrations and discharges can cause serious damage and even kill plants and animals downstream. Disposal of saltwater swimming pool and spa water must be hauled via truck to a proper waste facility,” says the City of Ventura Public Works.

Draining a saltwater pool is not only a hassle but can be illegal in certain counties since the buildup of salt in soil puts animals, vegetation, and freshwater at risk.

NEXT STEPS: A POOL SANITATION SYSTEM WORTH ITS SALT

Are saltwater pools worth it? You don’t need to consult Siri on this one; just revert to the overarching chemistry of salt that seasoned my opening argument: “Na.” 

Salt Systems sprinkled onto the scene by capitalizing on the perceived natural benefits for the skin (this was long before TikTok and viral skincare gurus, circa 1960). However, this myopic view of saltwater sanitation systems is a misleading emotional appeal. 

As well-seasoned pool builders, we strongly advise against using salt generators. Even the newer systems that require lower salt levels raise concerns, particularly regarding newly installed pool surfaces. Salt manufacturers recommend a minimum waiting period of 30 days before adding salt to a pool. This recommendation undergirds an awareness of salt's ability to erode pool surfaces prematurely, reinforcing the crux of our stance and this article’s title: the corrosive argument against saltwater pools.

We love a full-circle moment.

The good news is that there are better alternatives that have been around for decades. Check out the articles below for more information on different pool sanitation systems!

SALTWATER VS. CHLORINE: WHICH IS BETTER FOR MY POOL?

WHAT'S AN OZONE GENERATOR? AND WHY IT'S GREAT FOR YOUR POOL