Maintaining a saltwater pool

by Sally Bouorm | April 1, 2010 8:19 am

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By Bob Harper

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Saltwater pools are becoming increasingly popular in Canada. People love the soft, soothing feel of salt water, which is gentle on eyes, nose, skin and hair compared to traditional pool sanitizers. Pool owners also do not have to transport, store and handle harsh chemicals. And they perceive maintenance to be easy and convenient.

Yet, the unique chemistry and equipment of saltwater pools can pose a number of challenges, including staining, scaling, corrosion and damage to pool finishes and equipment.

To better understand the technical and business issues surrounding these pools, this author’s company conducted more than 300 interviews with builders, retailers and service companies and

commissioned independent research on the quality and purity of pool salt from all major North American producers.

This research pointed to some interesting misconceptions in the marketplace about how salt water pools work, and the impact that certain kinds of salt can have on the pool.

Saltwater pools have complex chemistry and are actually much different than traditionally sanitized pools, despite the fact chlorine is the sanitizing agent in both kinds of pools. With traditional pools, chlorine and other chemicals are regularly added to the water as sanitizers and to control algae, staining and other potential problems. In saltwater pools, chlorine is automatically produced by the electrolytic chlorine generator (ECG), which converts salt to elemental chlorine through electrolysis. Pool owners simply add salt to maintain proper salinity levels throughout the season.

All Salt Is Not the Same

Generally speaking, staining, scale, and turbidity can often be attributed to the kind of salt used in the pool, as well as overall water balance. Salt can vary widely in levels and types of contaminants depending on where and how it was created. Salt is added to fresh water pools at levels of 3,000 to 4,000 parts per million, so a 20,000 gallon pool will require 530 pounds of salt at startup (to achieve 3,200 parts per million). With quantities that large, even salts that claim 99 percent purity can add up to 5.3 pounds of contaminants in the pool. These contaminants can slow dissolution rates and cause all kinds of maintenance problems, including staining, scale, and chlorine demand.

There are three kinds of salt that may be present in commodity pool salt:

Solar salt

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Is created from the natural evaporation of saline ponds by wind and sun, may contain a host of organic contaminants that can cause turbidity and chlorine demand in the pool. Since an ECG has a fixed maximum rate of chlorine output, it can have a very difficult time overcoming the chlorine demand. Solar salt may also contain inorganic contaminants that cause staining and scale formation.

Rock salt

This is actually unrefined mined salt, may contain large amounts of inorganic contaminants such as manganese, copper, iron, nitrates, silicates, sulfates, calcium, and metals. Many of these contaminants can affect water clarity, dissolution rate, stain and scale potential, and other important water balance factors. Rock salt also contains dirt and other insoluble matter. For these reasons, it should never be used in swimming pools.

Mechanically evaporated salt

Often called “food grade” by the industry, this salt is created by the forced evaporation of saturated salt brines under controlled conditions. Mechanically evaporated salt is best for saltwater pools because it is purer than rock salt and solar salt. But don’t let the terminology confuse you. You would never add food salt to a pool; it usually contains iodine and anti-caking agents, such as YPS, that can cause issues in swimming pools.

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Not all mechanically evaporated salt is equal, as some forms contain higher levels of contaminants than others. Where your salt was created is equally important as how it was created. Interestingly, Canada has some excellent mines that produce very high-quality salt. Mechanically evaporated salt from Compass Minerals’ Sifto facility in Amherst, Nova N.S., with all other leading North American salt producers. (This salt is used in a new saltwater pool product called Pristiva™, which is available in the United States and should be available in Canada within the next few years.)

It can be difficult to determine what kind of salt is in commodity pool salt. Some brands use salt from many different sources, which can vary from region to region. Most brands use salt from whichever mine is closest to their final ship destination to minimize shipping costs. Pristiva is the only brand that guarantees that its salt comes from the same source in every bag.

Optimal Care and Maintenance

Salt water pools require less maintenance than traditional pools, but that doesn’t mean they are maintenance free. In addition to using the highest quality mechanically evaporated salt, you’ll need to test and balance your pool regularly.

For residential pools, we recommend weekly testing of pH and chlorine and monthly testing during the season of total alkalinity, calcium hardness, cyanuric acid, and metals. (Certainly, commercial pools should have their pH and chlorine levels tested more frequently.) In saltwater pools, testing and adjusting pH is very important because the electrolytic process for making chlorine constantly increases the pH. We also recommend monthly testing of salinity levels to ensure they are maintained at the proper level.

Using the highest quality mechanically evaporated salt plus testing and balancing your pool regularly will go a long way toward preventing the turbidity, staining, and scale that can harm a pool and create premature equipment failure. Instead, it will help pool owners get maximum enjoyment from their salt water pool while protecting their investment.

 

Bob Harper is general manager of pool products at North American Salt Company, a subsidiary of Compass Minerals. He has more than 20 years of experience in the pool and spa industry and is an expert in salt water pool systems. He can be reached via e-mail at harperb@pristiva.net[5].

 

Source URL: https://www.poolspamarketing.com/trade/maintaining-a-saltwater-pool/

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