For generations, chlorine has been the sanitizer of choice for swimming pools. No matter the size, shape or location of a given pool, unwieldy bags of chlorine have traditionally been as much a part of its upkeep as skimmers or drain covers.
But while chlorine itself is as important as ever for keeping pools clean and sanitary, recent years have seen a major improvement in how it’s created and managed. Salt chlorination is becoming much more common as an alternative to the practice of mixing pure chlorine with the water. This modernization is allowing pool owners to avoid storing chlorine and hauling it out to the pool whenever needed, and the common complaints of skin irritation associated with high levels of chlorine (as well as its smell) are also quickly fading into the past.
How does it work?
We spelled the out the science of electrolysis in a previous blog post. The basic idea is that a salt cell, which is attached inline to the pool’s plumbing returns, takes in saltwater and, with the help of an electrical charge (electrolysis), converts molecules of salt (sodium chloride) into hypochlorous acid, a mixture of hydrogen and chlorine gas. This eliminates the need for manually adding chlorine to the water.
It also means that at any given point in time there is both chlorine and salt in a saltwater pool. A common misconception is that the salt itself is keeping the pool clean and chlorine is no longer present - as we said, chlorine is as necessary as ever. A big advantage of electrolysis is that it’s also a reversible process, meaning chlorine will convert back to salt, thus reducing (though not eliminating) the need for adding salt over time.
The other essential part of a salt system is the power center, which provides the current that allows electrolysis to occur. The salt cell and power center are often bought together as a package, though there is another way to power the cell, as we will discuss.
What are the real advantages of saltwater?
Like we mentioned, salt systems eliminate the need for buying as well as storing chlorine, a bulky and fairly hazardous chemical with a strong clinical smell, around the house. But there are plenty of other reasons to switch to saltwater.
First, many swimmers prefer the softer feel of saltwater over the often irritating effects of free chlorine, such as red eyes and discolored hair. Many people associate saltwater pools with the experience of swimming in the ocean, but ideal pool salt levels are only roughly 10 percent (3,000-4,000 parts per million) of those in open saltwater, so such comparisons are not realistic.
Another strong motivation for switching to a salt system is that less maintenance is generally required for the pool. Not only is the need to manually add chlorine to the water eliminated, the salt cell (shown attached to a pool's returns below, between the filter and pump) handles a major part of upkeep by measuring the level of salt automatically. The power center's digital readouts alert the owner whenever there’s a problem.
Is it worth the upfront cost?
Buying a salt system (consisting, again, of a salt cell and power center) such as the Pentair Intellichlor or the Hayward AquaRite and having it professionally installed will generally cost a minimum of $1000, and that doesn’t include the expense and burden of handling the salt itself when initially converting your pool from free chlorine.
Traditional chlorine pools, in addition to the drawbacks we already discussed, typically require more supplemental chemicals such as stabilizer (cyanauric acid), to help keep it from evaporating in direct sunlight, and algaecide, particularly in the heart of summer. These generally add up to about $500-600 per year for areas with extended swim seasons.
Another way to leverage the initial cost of a salt system is to instead buy a larger automation package, such as the Pentair EasyTouch Intellichlor system, which itself includes a salt cell. This is an all-inclusive way of controlling essentially every element of your pool setup, including lights, pumps, heaters and valves (remotely turning the lights off or heating your pool or spa ahead of time, for instance), and comes standard with a cell which uses the EasyTouch console itself for its power. The EasyTouch thus offers all the functionality of a standard salt system and much more.
Check out our video on the many benefits of automation.
The process of installing a salt system (if automation isn't in your short-term plans) is really fairly simple. There are units for various pool sizes – Pentair’s Intellichlor, for instance, has separate models for pool volumes of 20,000, 40,000 and 60,000 gallons. If you don't already know your pool's volume, the formula for determining it is straightforward:
Volume = Length x Width x Average depth x 7.5
So for a rectangular pool that’s 20’ x 40’ with an average depth of 5 feet, the volume is (20 x 40 x 5 x 7.5) or 30,000 gallons. Professionals recommend upsizing when buying salt cells – in this case, going with the 40K gallon model – to keep less of a burden on the pool pump and on the cell itself.
Secondly, regular table salt (which is sold by the bag in hardware and home improvement stores) has to be added to the pool. Experts generally recommend 25 pounds of salt for every 1000 gallons of water to reach the desired mixture in parts per million, so our example pool of 30,000 gallons would need 750 pounds of salt! Remember, however, this is a one-time step and salt is much cheaper than chlorine (every bit as heavy, though).
Is saltwater a threat to my pool’s components?
Saltwater has a corrosive effect over time on lower-grade metals, such as aluminum, which are sometimes present in older heaters and older accessories like ladders and light fixtures. But generally, saltwater is no tougher on the pool’s pump, surface or deck than water with free chlorine.
A recent trend in the industry, in fact, is for products to be designated as “salt friendly”, basically meaning they contain stainless steel or at least no metals that would be affected by salt. If you have questions about specific elements of your pool setup, contact the manufacturer about their compatibility with saltwater. More and more, however, components are made to handle salt just fine.
The time is now
For some, there will always be comfort in the familiar, and the thought of moving away from standard chlorine pools is worrisome. For others, the commitment, both financially and in learning a new way of doing things, will keep them away converting to saltwater.
But cost is no factor in the long run, given that you'll be generating your own chlorine for years to come, and we routinely hear from customers delighted with their choice to switch to salt system chlorination.
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