Saltwater Vs. Chlorine Swimming Pools

For years, swimming pools have been synonymous with chlorine. Many people have childhood memories of heavily chlorinated pools. Burning eyes, itchy skin, and even green hair were all symptoms of too much time in the pool. Starting in the 1980s, another type of pool started to become available. These saltwater pools didn’t require the addition of chlorine. For many people who were sensitive to chlorine this seemed like a great alternative. But what really is the difference between saltwater and chlorine swimming pools? They may not be as different as you think.

Saltwater Vs. Chlorine Swimming Pools [infographic]

How a Saltwater Pool Stays Clean

If pool water was left completely untreated it would very quickly turn into an algae filled swamp. That is because standing water, like the water in a pool, is a perfect home for algae and bacteria. Explosive growth of algae and bacteria in a swimming pool would turn the water dark, slimy, and unhealthy to humans. The main way to prevent the growth of algae and bacteria is with the introduction of chlorine to pool water. The chlorine inhibits algae and bacteria growth and keeps pool water clean and clear.

But if chlorine is the main way to keep pool water from becoming overgrown with algae and bacteria, how does a saltwater pool stay clean? The answer may surprise you. What keeps a saltwater pool clean is chlorine! The difference between a chlorinated and a saltwater pool is in the manner in which the chlorine gets into the pool.

Where Does the Chlorine Come From

In a traditional chlorinated pool, chlorine is added manually, usually as a liquid or powder. To keep the chlorine levels in the pool water high enough to effectively sanitize the water, chlorine needs to be added regularly. The reason more chlorine needs to be added has to do with the way that chlorine is present in the pool water. This also has to do with the negative effects most people associated with chlorine.

The chlorine level in a pool is a combination of freely available chlorine (FAC) and combined available chlorine (CAC). The FAC is chlorine that is available to sanitize the pool water. The CAC doesn’t help sanitize the pool, but it does include chloramines. Chloramines are formed when FAC combines with amines from human sweat, saliva, mucus, urine, and other biological excretions. The chloramines are what produce the classic “chlorine smell”, as well as the eye and skin irritation people associate with chlorinated pools. The presence of excess chloramines results from too little FAC in the water.

In saltwater pools, chlorine doesn’t have to be manually added to the water, but it is still present. The chlorine is produced by electrolysis. Through electrolysis, chlorine is separated from salt (NaCl). This results in a constant supply of FAC. The electrolysis also burns off chloramines. The steady availability of FAC along with reduced levels of chloramines can reduce the negative effects of chlorine that occur in manually chlorinated pools.

Balancing Pool Water in a Saltwater Pool

Even though saltwater pools generate a constant steady flow of chlorine, chemical levels still need to be checked and manually regulated. The production of chlorine from salt releases hydroxyl ions, which increase the alkalinity of the pool water. To keep the water at a steady pH level close to 7.2, pH levels need to be checked regularly. Hydrochloric acid needs to be added to the water when the pH gets too high. The hydrochloric acid has the added effect of converting the molecules broken apart in the chlorine production process back into salt (NaCl) which can then be broken back apart to create more chlorine.

A saltwater pool may also require the addition of a stabilizer to keep the chlorine from being broken down by UV rays from the sun.

Maintenance of a Saltwater Pool

In addition to monitoring pool water for pH, the saltwater generator in a saltwater pool requires some maintenance. The electrodes that separate out the chlorine from the salt in the pool water can also attracts other minerals. This causes a slow but steady buildup of minerals such as calcium on the electrodes. This buildup needs to be washed off periodically. The electrodes are treated with a mild acidic solution to remove the minerals. Using a solution that is too acidic can damage the electrodes, leading to an expensive replacement. Running the generator with too little salt in the water can also damage the electrodes.

One simple mistake that can damage a saltwater pool is using the wrong acid to balance the pH. As the pH level in a saltwater pool rises, it becomes necessary to add an acid solution to bring the pH back down to 7.2. But only Hydrochloric acid should be used for this. That’s because the reaction that removes the chlorine from the salt is basically reversed by the addition of hydrochloric acid. That allows the chlorine to recombine into NaCl and the whole process can start again.

Adding sulphuric acid will reduce the pH, but will produce the wrong type of ions. These sulphate ions will conduct electricity at the electrodes of the saltwater generator, but won’t produce any chlorine. This can completely short-circuit the chlorine production method of a saltwater pool. A pool that has had too much sulphuric acid added may need to be completely drained and refilled with new water.

Other Concerns With a Saltwater Pool

In a saltwater pool, calcium and other minerals may naturally build up, causing scaling on pool surfaces. If the water is not properly balanced the salt itself can cause buildup. Scaling is hard to clean, and may require draining and even acid washing to fully remove the calcium buildup. Salt buildup can damage metal fixtures in the pool. Rails, ladders, and other metal fixtures in a pool can become rusty from too much salt exposure. Salt exposure will also usually void the warranty on these products.

Is a Saltwater Pool Worth It?

The determination of whether a saltwater pool is right for you should include several factors. First is cost. The initial cost of a saltwater pool is higher than a traditionally chlorinated system. However, over time there may be savings due to the fact that you don’t need to buy chlorine. Salt is much cheaper than chlorine.

Another consideration is maintenance. Saltwater pools don’t need to be regulated for chlorine, but are not maintenance free. pH levels need to be maintained and the electrodes in the saltwater generator need to be cleaned from time to time. Stabilizers may also need to be added to the water to prevent the sun’s UV rays from causing the chlorine to dissipate too quickly.

The advantage of a saltwater pool is mainly in the type of chlorine in the water. The consistent production of FAC and the burning off of chloramines reduce the typical negative effects associated with chlorine. However, to call a saltwater pool chemical free, or even chlorine free, would be inaccurate.

Installing a Saltwater System

If you are interested in installing a saltwater system for your pool, The Pool Butler can help. Our technicians can inspect your pool and give you a quote on the installation and maintenance of a saltwater system. We can also help educate you on the advantages and disadvantages of the system. In the end, the choice to install a saltwater system is yours, and depends on how much you value the advantage and disadvantages. But if you are ready to install a system, you can trust The Pool Butler to do it right. Contact The Pool Butler today to get started on your saltwater generation system. If you already have a saltwater system, our technicians are trained to maintain the system and keep your pool water balanced. Whatever your swimming pool needs are, The Pool Butler has got you covered.

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