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A Saltwater Filter for Your Pool or Spa: Should You Take the Plunge?

If you are planning to install a new swimming pool or hot tub or thinking about upgrading your current swimming pool or hot tub sanitation system, or just interested in keeping up-to-date on the latest in swimming pool and hot tub innovations, then at some point you will be faced with the sometimes confusing decision about how to sanitize and filter the water.

What is a Saltwater Filter?

There are several new options on the market these days. In this article we will cover only one of those options: a saltwater sanitation system.

For some, the term salt water as a means of sanitation for swimming pools and hot tubs conjures up images of swimming or soaking in salt water equivalent to ocean water. The idea sounds very ‘natural’. They think that salt is acting as a sanitizer as opposed to chlorine. This is not the case. Simply adding salt to your pool will not sanitize the water. You would not be swimming or soaking in water that has the same salinity as ocean water. If you have ever experienced getting salt water in your eyes or on a cut, you know how that stings! That is not the kind of experience you would want while swimming in your pool or relaxing in your hot tub. The salinity of a swimming pool or hot tub running a salt water sanitation system is about 1/10 of that found in ocean water, and less salty than a teardrop. 1

In fact, a saltwater sanitation system uses chlorine to sanitize your pool and hot tub, so it’s not really a ‘greener’ solution, but the process by which the chlorine is added to the water is what makes saltwater sanitation appealing to many swimming pool and hot tub owners.

How Does a Saltwater Filter Work?

Rather than having to continually add chlorine to your swimming pool or hot tub manually, a saltwater system produces the chlorine internally and continually, using salt to produce chlorine. Salt (sodium chloride) is dissolved in water and the sodium is separated from the chloride and produces chlorine through the process of electrolysis as it passes through an electrically charged cell. The chlorine gas, (Hypochlorus acid), dissipates through bubbles, and sodium hypochlorite provides the water sanitation benefits. The constant availabilty of free chlorine produced by salt water electrolysis helps to prevent the build up chloramines which often cause irritation to skin and eyes in traditonally chlorinated swimming pools and spas (For further explanation see “Salt Water Chlorination” at:

Using a saltwater chlorine generator does not completely eliminate the need to add chemicals to your pool, such as pH balancers, and stabilizers. In fact, they are crucial to the functioning of the system. When hydrochloric acid (HCl) is added to balance the pH, the chemical reacts with the presence of sodium hydroxide (NaOH) released during electrolysis and produces NACl i.e. salt, and the entire process repeats itself.

A salt water chlorine generator converts the salt to chlorine and back to salt over and over. You will not need to add more salt unless there is splashing out or backflushing sufficient to necessitate adding more water to the swimming pool or hot tub. This is considered to be another advantage of using salt to produce the chlorine because salt is relatively inexpensive and after the initial dose, it only needs replaced occasionally, and you will not need to store, handle, or purchase large quantities of noxious chlorine tablets or powder.

The initial cost of a salt electrolysis cell and chlorine generator is generally higher than traditional swimming pool and hot tub filter set ups, but many swimming pool and hot tub owners believe the benefit of not having to chlorinate manually and the decrease in eye and skin irritation, are worth the costs.2

Are There Drawbacks to a Saltwater Filter?

Salt can act as a corrosive element on certain surfaces and can harm delicate ecosystems and animal life so it’s important to have an expert design your pool and surrounding landscape. Your installer should use materials and plantings that will not be adversely affected by any salt residue caused by splashing and evaporation. Backflushing must be properly performed to avoid draining into delicate ecosystems. Keep in mind though, that the salinity of the water in a saltwater sanitation system is very much diluted compared to ocean water and with thoughtful design and proper maintenance, these potential problems can be addressed.

Naturally, as with all swimming pool and hot tub sanitation and filter systems, proper maintenance and cleaning is essential to keep everything running smoothly. Replacement of the cell will be necessary after several years and because of the cost of the equipment you will want to follow the installers suggested maintenance schedule

How Can I Experience a Saltwater Filter Before Buying?

The choice to go with a saltwater sanitation system is a personal one, and the benefits and challenges are also particular to location and the design of your swimming pool and hot tub and the materials used in their construction. If you are upgrading rather than installing a new swimming pool or spa, then your expert installer will want to make sure older parts of your current system are compatible with a saltwater system, or upgrade those accordingly. A one size fits all approach is not recommended. It’s important for you to discuss your options with a Seven Seas Pools & Spas expert. Once the decision is made, maintain good communication with your installer and do regular maintenance checks to insure that you continue to reap the benefits of your decision and avoid any undesirable results. This is imperative regardless of which kind of filter system you use. Seven Seas Pools and Spas can answer any questions you have and we look forward to providing all of your installation and maintenance needs.

One final suggestion before you take the salt water plunge: some hotels and resorts are using salt water to sanitize their swimming pools and hot tubs. Why not book a night at such a location and experience the difference for yourself?

If you currently have a saltwater chlorine generator or are considering installing one, Seven Seas Pools & Spas welcomes your comments or questions below.


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