To Salt Or Not To Salt

The ups and downs of saltwater chlorine generation

By David J. Cantlin

Although saltwater chlorine generation has been used in the pool industry for some time, it has only recently been making its presence known in commercial recreation.

Among its claims:

• Clean on-site production of chlorine

• No storage of large amounts of chlorine

• Bather comfort

• Elimination of chloramines

• Ease of maintenance.

Clean On-Site Production Of Chlorine

The most common type of saltwater chlorine generators have enclosed chambers that contain metal plates powered by low-voltage electricity. These “cells” are normally plumbed on a bypass line somewhere on the return recirculation line of the swimming pool. Salt (normally a food-grade variety), is added directly to the water to a level of about 3,000 parts per million (ppm) depending on the manufacturer. As the demand for chlorine increases, the metal plates in the cell are charged. The saltwater passes through the electric field of the charged plates, and a chemical reaction takes place, turning sodium chloride (salt) into sodium hypochlorite (bleach).

No Storage Of Chlorine

The most immediate benefit of a saltwater chlorine generator is that large amounts of chlorine are no longer stored on-site. At our facility, we use gas and liquid chlorine to sanitize three pools. On any given day, we have hundreds of pounds of gas chlorine and at least 40 gallons of liquid chlorine stored in the facility--a potential problem if either product starts leaking. The tradeoff is that today I have 49 50-pound bags of food-grade salt stored in the old gas chlorine room, but I don’t have to worry about leaks. We still have some liquid chlorine on site, but it is limited to about 8 gallons, and is mainly used by pool staff to sanitize decks at closing.

Bather Comfort

Another benefit is that the salt in the water actually seems to soften patrons’ skin--and they rave about it. Many patrons tell me they love that we switched to salt and eliminated chlorine. I gave up trying to explain a long time ago that we actually did not get rid of chlorine, but were now producing it in the pool. The bottom line is bathers seem to enjoy their experience in our facilities even more since the switch.

Elimination Of Chloramines

Chloramines are the four-letter word of all professional pool operators. We have all been to pools where you can smell the chlorine when walking into the facility, and if the situation is really bad, your eyes burn as you swim. Many swimmers wrongfully attribute this to too much chlorine in the water, but the case is normally in the other direction. The chlorine has combined with an organic and become a chloramines compound, which is actually an ammonia byproduct. Despite what a salesperson says, saltwater chlorine generation is no more effective in dealing with chloramines than other chlorine products, thus the reason I keep some cheap granular on hand.

Ease Of Maintenance

Maintaining a saltwater chlorine generation system is relatively easy, especially if you have an “in-line” system. Cells normally require a short acid bath two to three times a year depending on use and water chemistry. This removes scale buildup on the plates, which can affect the efficiency of the cells’ operation. With inline cells, you simply have to pull the cells from the line and clean them, which is normally a 15- to 20-minute operation. Again, a positive selling point is the pool operator is not exposed to chlorine. Other maintenance includes ensuring that electrical boards and power supplies are functioning.

The Down Side

With any sanitizer system there is a “downside.” For saltwater chlorine generation, there are two issues to consider--corrosion and isolation.

Even though the salt levels are relatively low, there is a noticeable increase in corrosion of some pool equipment. Chlorine by itself can be corrosive to some metal items in an aquatic setting; add salt and there is a slight escalation of the problem. But it is manageable, requiring that you pay closer attention to the chemistry. Our biggest issue was with heater vessels. In recent years, the manufacturer had included a thinner wall on the vessel, and this was highly susceptible to corrosion with the addition of salt. We solved this issue by having a private machine shop build a thicker-walled vessel, a relatively cheap fix.

The other issue a pool operator must face when straying away from simple chlorine sanitizing is relying on the original source of purchase for any system needs, which means he or she is at the pricing mercy for the lifetime of the product. You can’t go to the local pool-supply store and buy salt cells or other replacement parts for the system. If you use chlorine tablets, you can go anywhere, including a local warehouse store to make a purchase.

If you are trying to get away from chlorine storage and find a cleaner way to sanitize a pool and still use chlorine, saltwater chlorine generation is very effective, as the cons are very workable. To salt or not to salt? It does work, but know what you are getting into.

David Cantlin is the Facility and Operations Manager for the city of Fife Parks Department in Washington. He has been involved in the aquatic industry since 1988. He can be reached via e-mail at dcantlin@cityoffife.org