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.