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Saltwater Pool Maintenance

A guide to caring for your saltwater pool

By Dennis Gray

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Saltwater pools have become popular in Canada. A growing number of pool owners prefer the experience of swimming in saltwater, which, compared to traditional pools, tends to be gentler on swimmer’s eyes, nose, skin and hair. Some like the fact that there is less need to transport, store and handle harsh chemicals, while others find maintenance to be easier and more convenient than traditional models.

However, while saltwater pools have grown quickly in popularity, knowledge about how to best care for them has not kept pace. If you choose a saltwater pool for your backyard, you need to understand the unique water chemistry and equipment involved, which has different characteristics and maintenance requirements compared to traditional pools. Without the proper upkeep, you will not be able to truly enjoy the benefits this technology has to offer.

A saltwater pool primer

To get the most enjoyment from your saltwater pool, it is important to understand what’s really going on inside it. In traditional pools, chlorine and other chemicals are regularly added to the water. These agents work as sanitizers, controlling algae (algistats), staining and other potential problems.

In saltwater pools, chlorine is automatically produced by an electrolytic chlorine generator (ECG), which converts salt to elemental chlorine through a process called electrolysis. Salt is added as needed throughout the season to maintain proper salinity levels (the correct levels are determined by the ECG manufacturer). Additional products are added periodically to keep pool water balanced and to minimize the potential for stains and scale buildup.

It sounds simple, but there’s more to it than meets the eye. Saltwater pools have unique chemistry and harsh conditions within the ECG. The interior of the ECG cells have extreme pH ranges (acidic on one end and alkaline on the other), high chlorine levels and temperatures that can climb to more than 49 C (120 F). These conditions are unavoidable and necessary for the chemical reaction that converts salt molecules into chlorine molecules; however, they can also break down many conventional pool treatment products as they pass through the generator, rendering them useless.

As a result, saltwater pools that are not maintained properly can be susceptible to problems such as staining, scale, cloudy water and increased chlorine demand. The following three tips will help you avoid these problems.

Tip #1: All salt is not created equal

There are many different kinds of salt, each of which has unique contaminants depending on where and how it was created. It is important to be aware of these origins, as certain contaminants can cause cloudy water, staining, scale and other water balance issues in your saltwater pool and equipment. After all, if you spend tens of thousands of dollars on a pool, you should protect your investment by using the highest-quality salt.

Rock salt

This type of salt should never be used in a swimming pool. It is actually unrefined mined salt, which may contain large amounts of metals and minerals such as manganese, copper, iron, nitrates, silicates, sulfates and calcium. 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.

Solar salt

Solar salt, which is also not recommended for saltwater pools, is created from the natural evaporation of saline ponds by wind and sunlight. It may contain a host of organic contaminants that can cause cloudy water and increased chlorine demand (or a chlorine deficiency) in your pool. Since an ECG has a fixed maximum rate of chlorine output, it can have a difficult time overcoming the need for more chlorine to battle these extra contaminants. Solar salt may also contain inorganic contaminants that cause staining and scale.

Mechanically evaporated salt

This is the best choice for saltwater pools because it is purer than rock and solar salt. It is created by the forced evaporation of saturated salt brines under controlled conditions. It is important to remember, however, that not all mechanically evaporated salt is equal; some forms contain higher levels of contaminants than others. While the overall amount of contaminants may be very small, they can add up quickly when adding hundreds of kilograms of salt at a time to your pool.

When selecting salt, always use a product labelled ‘pool salt,’ rather than those specified for water conditioning or some other purpose. Also, check with your pool retailer or service company to verify what kind of salt is being used in your pool.

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