Alternative Sanitizers

Alternative Swimming Pool Sanitation Technologies

Let us start by pointing out some basic knowledge about swimming pool sanitation methods and alternative sanitation equipment.


Unlike Europe, in the United States Chlorine has traditionally been the most accepted swimming pool sanitizer. However, credible research suggests that Chlorine has serious health issues when used in standard recommended quantities as a swimming pool sanitizer.

Chlorine combines with organic load created by human use (sweat, urine, etc.) of the pool and the environment (pollens, airborne debris, etc.) resulting in Chloramines and Trihalomethanes. Research and health agencies have produced evidence that Chloramines and Trihalomethanes may be carcinogenic and could be linked to different cancers. There is also credible research that may link Chlorine/Chloramines off-gas effects at surface level of swimming pools to Childhood Asthma.

A quick history lesson tells us that chlorine gas was responsible for killing several hundreds of thousand soldiers in World War I.

Why then in the United States, does Chlorine remain the dominant sanitizer in swimming pools and why is it that pool professionals do not promote proven, healthier sanitation solutions?

Several facts come to mind:

One fact is that human nature is to “stay in your comfort zone”. Many pool companies have been accustomed to Chlorine as a sanitizer for many years and they feel comfortable with what they know.

Another common reason is that some pool companies which rely upon chemical sales as a source of revenue do not wish to provide solutions which drastically reduce chemical revenues.

An important explanation may be lack of knowledge or training on alternative solutions to Chlorine as a solution to overall pool maintenance. Ozone generator companies share some of the responsibility for this because they have not educated pool owners sufficiently enough to create a need for dealers and builders to learn more about the benefits of Ozone.

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A Salt-Chlorine generator is based on an electrolysis process during which Sodium Chloride is converted to Sodium Chlorine by passing across metal plates enclosed in a chamber (referred to as “salt cell”) which is installed in-line on swimming pool plumbing. These metal plates are energized by a low electrical current which causes the electrolysis process of ion exchange of chloride to chlorine.

At present, Salt-Chlorine generators are very popular in the United States for installation on residential swimming pools, and have been for approximately five years. They surfaced in the market previously a number of years ago as well, but faded in popularity nearly as quickly as they appeared.

There are several issues with these type units:

“Maintenance” and “Misconception” by pool owners.

Maintenance: The metal plates have a tendency to calcify which requires periodic cleaning with Hydrochloric acid (Historically called Muriatic acid). Hydrochloric acid must be handled with appropriate safety precautions because it is a highly corrosive solution with special risk to soft tissues such as the eye. Salt cells are also very costly when they need replacement.

Another maintenance issue with swimming pools using these type systems is the need to frequently adjust pH levels.

There are also situations where the demand for Chlorine due to either high organic load (bather load, tree pollen, rain) or high ambient temperatures, can not be adequately maintained by the generator itself requiring addition of Chlorine or algae control products. A good solution to this problem in pools that already have Salt-Chlorine generators installed is to add an Ozone Joe’s Ozone Generator to reduce organic load, allowing the chlorine generator to run at a lower output rate.

One key drawback of Salt-Chlorine generators, especially those working in higher demand pools, is the corrosive effects. Salt in itself is corrosive and the effects of corrosion are a major point of customer dissatisfaction of pool owners with Salt-Chlorine generators. Research has shown that even stainless steel is susceptible to corrosion at 3,500 ppm. Pool ladders and other metal fixtures are affected by salt and the process is further enhanced by the low current being applied to the Salt-Chlorine generators plates. This is especially noticeable where dissimilar metals are joined. The corrosion process is known as “Galvanic” or “two-metal corrosion”.

Although fiberglass and vinyl liner pool surfaces may develop some issues, they may not experience the same damage that some builders report witnessing on concrete pool walls. In addition to the damage under the water level of the pool, there are also numerous issues reported with decking materials such as costly sandstone surfaces being damaged.

Misconception: Many pool owners are under the misconception that they have a “Chlorine free pool” when using Salt-Chlorine generator technology. After all, it is a saltwater pool, right? Wrong! Although the swimming pool does contain salt, and there is a smooth feel to some like salt in the Ocean (though these pools have less than ten percent equivalent of the salt in the ocean), the pool is Not Chlorine Free. The very purpose of this system is to produce Chlorine in the pool, without the physical handling of Chlorine.

In addition, as our society continues to move toward a more environmentally friendly stance, future legislation may require additional remediation requirements on saltwater pools as the backwashing of saltwater pool filters may be of concern to local vegetation, drainage systems, and the aquifers in some geographic locations.

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The Ionization process is based on using antibacterial metals such as copper and silver. This process will reduce overall Chlorine usage due to the metals performing some of the organic workload.

There are electrolysis based Ionizers and mineral blocks impregnated with antibacterial metal based Ionizers. The electrolysis Ionizers require periodic cleaning and replacement of the generator probes. The mineral block Ionizers require periodic re-purchase of mineral blocks. So, both technologies add additional and re-occurring costs.

Ionizers cause flocculation of organics in a pool which does allow for particles to be filtered. The downside to electronic ionizers is that this process often times results in a staining of pool surfaces at the water line, often times permanently.

Ionizers have shown reduction in Chlorine requirements, but at similar Chlorine maintenance costs.

Many pool industry professionals feel that combining the Mineral Technology with an Ozone Generator is the easiest way to maintain a pool.

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This technology is often confused with Vacuum Ultra Violet Ozone Generator systems. They are in fact two very different technologies. Both technologies use lamps that operate in the UV light spectrum. Germicidal lamps produce output near the upper end of the UV-C spectrum at 253.7 nanometers. Ozone generating lamps operate just below the UV-C spectrum at the 185 nanometer range.

Germicidal UV lamps are used in water treatment and in air treatment such as HVAC air intake ducts.

For purposes of this discussion, we will discuss water applications only.

Germicidal UV is used in many water purification systems such as ponds, swimming pools, water treatment plants and home drinking water systems.

The application consists of placing a Germicidal UV lamp in a clear housing. This housing is then directly installed into the plumbing. Water and many contaminants contained in the water are exposed to the glow from the lamp. Many manufacturers of this technology state a microorganism kill rate of 91% with some as high as 99% of the organisms actually exposed to the glow.

There are several issues with this technology. One is initial cost, another is ongoing maintenance and lamp replacement costs, and another is clarity of the water being purified.

Initial product cost and installation cost is greater than other technologies.

Lamp replacement is another issue. Manufacturers state the lamp life requires the lamps to be replaced as often as every six months. Some allow ten to eleven months. While the lamp cost is one concern, the actual process of replacement cost is another as it is invasive to the plumbing.

Depending upon water clarity, not all contaminants will be exposed to the actual glow. This is due to light blockage from other contaminants, so kill rates will be lower. Remember, only contaminants visible to the lamp glow are affected.

One issue that exists is the accumulation of debris or chemicals on the surface of the lamp cartridge hindering exposure to the glow. This requires a periodic cleaning to obtain the full benefit of the system. Some manufacturers have addressed this by installing an actual wiper that transverses the light column automatically, which is additional initial and ongoing cost, and may not totally correct this issue.

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Ozone technology for swimming pools has been in regular use for over 50 years in places like France, Germany and other European nations as they realize the consequences of Chlorine gas.

Ozone has also been in use in Europe since the 1890’s for drinking water purification. Some large cities in the United States such as Los Angeles and Milwaukee now boast the best drinking water in America since they began using Ozone as a purification method. It is difficult to find bottled water that has does not use Ozone as a purification method.

Ozone, although a disinfectant (sanitizer) and oxidizer, it is normally referred to as the primary oxidizer and alternative sanitizer when referring to its use in swimming pools in the United States.

Ozone destroys viruses and bacteria such as e-coli and legionaries, and others.

Ozone is over two thousand times faster acting than Chlorine at oxidizing and destroying bather load in a swimming pool. This drastically reduces chlorine requirements.

The advantages of using ozone in a swimming are many.

Decreased chemical usage - significant savings considering the cost of chlorine Better water clarity Reduction or total elimination of chloramines Reduction or total elimination of odors - particularly valuable in indoor pool environments Smoother water feel No red itching eyes normally caused by chloramines Very effective at destroying viruses and organisms pH neutral Ozone is a gas which consists of three oxygen atoms and is referred to as O3. Ozone has a very short life cycle and must be produced on site at the pool location. Ozone is created by a process where O2 Molecules are divided into two 01 atoms. Oxygen diatom or O1 does not exist alone naturally. What occurs after the splitting of the O2 molecule is the newly created O1 immediately loosely bond to available O2’s forming O3 molecules.

The loosely bonded O1 departs the O3 and attaches to any organic which results in oxidation of the organic (basically very rapidly disrupts the DNA/RNA structures). The O2 is released as O2 and the contaminate that was oxidized by the O1 is destroyed.

Ozone gas is introduced into water by means of either a venturi injector creating a vacuum to suck ozone gas into the water or with direct injection or diffusers by pushing the air into the water with an air pump. The Ozone gas mixes with the water. The best saturation of Ozone in water is obtained when many fine bubbles of Ozone is introduced which provide more total surface area of Ozone contact.

There are basically two ways that Ozone is produced by man or by nature. One is known as Corona Discharge (CD) and the other is passing air across special Vacuum Ultra Violet lamps. (VUV) often times referred to as UV Ozone or Very Ultra Violet Ozone.

Manufacturers of each of these technologies say the other technology uses more electricity. In reality they are pretty equal. In some applications VUV lamps use less and others Corona uses less, but in any event, not by much and not an issue. Neither uses much electricity.

Another statement by manufacturers is ease of maintenance between the two technologies. This is also subjective and used by who is selling what. Corona manufacturers require replacing check valves and hoses annually, and to wear protective gloves when doing so. Corona cell components also need periodic maintenance. VUV Lamp Ozone manufacturers state their lamps run between 9,000 and 20,000 hours, so they may need replacing depending upon pool filtration run time every several to seven or so years.

Both Vacuum Ultra Violet lamp Ozone systems and Corona Discharge systems are available for use in commercial swimming pools ranging to the millions of gallons.

Extremely large Corona Discharge systems are used for large metropolitan municipal water treatment systems.

Although this discussion is dealing with swimming pools, there are many applications for both Ozone technologies such as, but not limited to, water cooling towers, laundry systems, drinking water, wells and cisterns, wastewater treatment, aquariums, fruits and vegetables, meats, odors, medical, ice machines, many more.

The two technologies, CD and VUV, are briefly discussed below.

Corona Discharge (CD) Ozone Generators

Corona discharge is a high electrical energy field such as lightning in natural occurrences, and by man using two highly energized metal or ceramic plates or chambers with a narrow gap in which air flows through. The arcing of this high electrical energy called the corona field alters the electron structure of all elements in the air passing through the chamber.

When man made corona discharge ozone generator systems are fed pure oxygen input and also very dry air passed through an air drier, they produce high quantities of Ozone. When manufacturers of Corona Discharge Ozone systems provide Ozone output production graphs, they sometimes use pure oxygen and very low humidity or dry air in testing. At a minimum, they often use drier air than normally found in many areas of the United States.

In reality, Oxygen concentrators and air dryers are price prohibitive for the backyard pool so ambient air only is passed through the cell. Pure Oxygen does not exist in ambient air, and in some areas of the country, humidity is very high. Commercial CD systems that can afford the cost, and do provide Oxygen concentrators require additional maintenance such as cleaning concentrator filters, and life cycle issues. They also require Ozone monitoring safety devices.

(Ambient air: A colorless, odorless, tasteless, gaseous mixture, mainly nitrogen (approximately 78 percent) and oxygen (approximately 21 percent) with lesser amounts of argon, carbon dioxide, hydrogen, neon, helium, and other gases. b. This mixture with varying amounts of moisture and particulate matter, enveloping the earth; the atmosphere.)

Corona Discharge systems provided with ambient air input to the chamber such as backyard pools have certain issues that arise. Below are two primary issues.

One issue is the high Nitrogen content of ambient air. As mentioned previously, all elements passing through a Corona chamber are altered. Nitrogen is the primary substance in air, and altering its state creates harmful byproducts such as nitric acid (nitric acid: A clear, colorless to yellow liquid that is very corrosive and can dissolve most metals. It is used to make fertilizers, explosives, dyes, and rocket fuels) and Nitric oxide (nitric oxide n. A colorless, poisonous gas), along with other Nitrous byproducts. To top it off, Nitrates. Nitrates are Algae food.

Another issue is Humidity. Ever wonder why it is that when you reach for something or someone in the winter time where the air is dry and you are zapped by a bolt of static electricity? Ever wonder why in the summer time, or when outdoors this does not occur? These answers are simple—Ambient Air Humidity. If humidity affects electrical conductivity in ambient air, could it not directly relate to the electrical field in a Corona Discharge cell hindering output?

In review: Corona Discharge systems that are supplied pure Oxygen and dry air produce high levels of pure Ozone. Corona Discharge units that are provided only ambient air, such as backyard pool applications, create Nitrogen byproducts and may experience diminished outputs with increased humidity.

Vacuum Ultra Violet (VUV) Ozone Generators

VUV lamp Ozone generators simulate nature’s way of creating the Earth’s outer Ozone layer. This is accomplished by creating the equivalent of the Sun’s solar light energy spectrum in the 185 nanometer range.

The outer Ozone layer is a continual process of the spectrum interacting with Oxygen and is considered very beneficial to our existence.

There are differences in Ozone generation using VUV lamps versus Corona Discharge (CD) equipment.

Ozone lamps are not affected by humidity. In fact, humidity is said to increase the effective oxidizing potential of Ozone generating lamps by drawing properties of the germicidal spectrum through the filtering quartz. Some refer to this as Advanced Oxidation Technology (AOT) and others Advanced Oxidation Process (AOP). Ozone lamp systems perform very well in humid places, where there are issues with ambient air CD systems.

As with CD technology, the greater and purer the Oxygen amount introduced to the input chamber of the lamps, the higher output of Ozone.

Unlike CD systems that create potentially harmful Nitrogen byproducts with ambient air, Ozone lamps only alter Oxygen converting it to Ozone. Ozone lamps are not known to create harmful byproducts.

Ozone lamp systems normally do not require the maintenance of CD systems. The nitrogen byproducts created by CD hinder the effectiveness of check valves, injectors, and hoses which is not as evident with lamp Ozone generators. No special clothing or gloves are required for maintenance of lamp Ozone systems. Note: Do not look directly at an Ozone lamp. Ozone lamps also contain mercury, so proper disposal must be considered.

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In review:
  • VUV Lamp Ozone generating systems perform very well in all environments.
  • They normally require less maintenance than CD systems.
  • Warranties are often longer in duration.
  • Ozone lamp systems are normally less expensive to purchase.