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The 6 Best Pool Chlorine Alternatives [Pros and Cons]

by | Home Improvement

Pools attract all kinds of pathogens and while most of them are harmless to humans, some are potentially hazardous and can cause really serious health issues. Chlorine is a very popular and inexpensive chemical used all over the world to kill germs in pools. Its popularity is not surprising: it really does a great job.

While chlorine is a really effective chemical, using it to keep your pool clean comes at a price. In certain cases, it has a strong smell and it can irritate your skin and eyes. It also requires that you regularly check and adjust your pool’s pH level, otherwise it becomes less effective.

If you want to keep your pool clean without chlorine, you’re not alone. There’s an increasing demand for products that can serve as a reliable and safe alternative to chlorine. In this article, I’ll show you the pros and cons of the most popular chlorine free and low chlorine pool systems to help you find the one that suits your needs best. You can choose from quite a few pool chlorine alternatives, so it’s advisable to learn about the possibilities before making a decision and investing in a new system.

1. Bromine

If you want your pool to be free of germs, you must use some kind of sanitizer. Basically, the most common sanitizers are chlorine and bromine. Although chlorine is more popular, bromine can often serve as a reliable alternative.

Bromine, similarly to chlorine, is a highly reactive halogen element and a powerful sanitizer. Its natural state is a liquid that evaporates easily at room temperature. It’s extracted from brine pools on the ocean basin and it’s available in the form of tablets at stores.

Advantages of Bromine

Bromine has many advantages over chlorine, however, it has its own limitations as well. While chlorine can often cause skin and eye irritation, bromine is considered to be a safer choice (however sometimes bromine can also cause similar symptoms in sensitive pool users).

Another benefit of using bromine to disinfect your pool is the absence of unpleasant chlorine smell. Although bromine is not odorless, its smell is less noticeable and easier to tolerate. This is why it can be a great choice for indoor pools and spas where unpleasant odors can accumulate easier than in the case of open-air pools.

Chloramines are byproducts of the reaction of chlorine molecules and certain types of organic substances (like skin cells, urine, saliva or sweat) that are present in your pool. Chloramines are way less effective sanitizers than chlorine and when managed improperly they can cause several health issues, like eye irritation or respiratory problems (source). So if you use chlorine to sanitize your pool, you have to frequently eliminate chloramines from the water to keep it safe for the users that usually can be done by adding large doses of chlorine (it’s also called a chlorine shock or super-chlorination).

On the other hand, bromamines, that are formed when bromine molecules react with organic substances, keep their sanitizing effects and unlike chloramines, they actively continue to eliminate bacteria and other germs.

Another advantage of bromine is that it’s more stable in hot water than chlorine: while bromine can effectively eliminate germs until the water temperature reaches 130-140°F, chlorine is most powerful below 65-75°F. That’s why bromine is one of the most recommended sanitizers to use in hot tubs and spas.

Bromine remains active even at higher pH levels, while chlorine becomes much less potent. For instance, at pH 7.8, about 75% of chlorine is in an inactive form, while bromine does its job efficiently (source).

Disadvantages of Bromine

Bromine tablets cost more than chlorine ones, however, they remain active longer in the water (especially in the case of indoor pools and outdoor pools with an automatic pool cover). Also, bromide ions can be reactivated into bromine molecules by applying a chlorine or a non-chlorine shock treatment. This way you’ll need fewer bromine tablets.

One major disadvantage of bromine is that it’s not stabilized as effectively against UV light as chlorine. Therefore, in the case of outdoor swimming pools, you have to add bromine frequently because of the increased degradation. Obviously, this means greater expenses. At the same time, if you use bromine you don’t have to add cyanuric acid to the water that’s used to stabilize chlorine from sunlight. This can be an advantage if you want to reduce the number of chemicals in your pool.

Another disadvantage is that while you can easily and cheaply add chlorine tablets to your pool’s water (all you need is a simple floating chlorine dispenser), you should get an automatic erosion feeder to dissolve bromine adequately in the water that is an extra expense.

Pros and Cons of Using Bromine to Sanitize Your Pool In a Nutshell:

Pros:

  • It’s less likely to cause skin and eye irritation than chlorine.
  • No chlorine smell.
  • More stable than chlorine in hot water and at higher pH levels.
  • Bromamines keep their sanitizing effects.
  • Bromide ions can be reactivated, thus you’ll need a fewer amount of bromine tablets.

Cons:

  • Bromine is more expensive than chlorine.
  • It’s not UV resistant and can degrade easier and faster than chlorine in outdoor pools.
  • It may give a slightly noticeable yellowish color to the pool water.

Non-chlorine pool

2. Ozone Generator (Ozone Pool System)

Simply put, ozone (O3) is active oxygen. It’s highly reactive, therefore it’s an effective sanitizer that kills all kind of germs (including viruses). Ozone is used to purify pool water for decades and it’s popular for a reason: besides being extremely powerful, it leaves no traces in the water because it converts back to pure oxygen rather fast. So, unlike chlorine, ozone has no toxic byproducts.

How does an ozone pool system work? An ozone generator uses either ultraviolet light or a corona discharge system (it uses high voltage electrical current) to produce ozone from oxygen molecules. Both methods are effective, however, the corona discharge system produces a larger amount of ozone using less energy and lasts longer than a UV light system. At the same time, in the case of smaller pools a corona discharge system may not be as cost-effective as a UV light system because of the high upfront cost.

In low concentrations, ozone is practically odorless and doesn’t do any harm to the pool equipment. It’s very gentle on pool users and makes the water feel soft and silky.

While ozone purifies water much faster and more effectively than chlorine, it has a very short lifespan (minutes or seconds) so there will always be areas in your pool that remain untreated for a certain period of time. Thus, if you use ozone purification, you still have to add some chlorine (or bromine) to your pool to ensure high water quality.

Pros and Cons of Using an Ozone Generator

Pros:

  • Ozone is a highly effective sanitizer.
  • It converts back to harmless oxygen without any toxic byproducts.
  • It’s gentle on your skin and eyes.
  • It also reduces the amount of iron and manganese in the water and it prevents calcium scaling.
  • It’s pH neutral, thus it doesn’t change the pH level of your pool.

Cons:

  • High upfront cost.
  • You still have to use a small amount of chlorine (or bromine) to eliminate all contaminants.

3. Biguanide Pool Treatment (PHMB): a Safe Pool Chlorine Alternative

If you want to make your pool completely chlorine free, you should definitely have a closer look at PHMB (it stands for polyhexamethylene biguanide). It’s an effective disinfectant and the only EPA-registered non-halogen sanitizer for pools. It does require no chlorine (or bromine) at all to work. Baquacil was the first trade name under PHMB was sold, however, after the patent expired newer products appeared on the market (like Revacil or Aqua Silk).

Biguanides are easy to use and safe alternatives to chlorine. They don’t cause skin or eye irritation and do not damage pool equipment. They’re stable molecules and aren’t affected by sunlight and changes in temperature or pH levels.

One of the biggest disadvantages of PHMB is that it’s not an oxidizer, that is to say, it can’t break down contaminants (such as dead skin cells, body oils, and other organic substances), thus you have to add hydrogen peroxide to the water to do the job. It’s recommended that you use algaecide as well to keep the water clear. Eventually, you also have to shock your pool with hydrogen peroxide.

Another disadvantage of biguanides is the maintenance cost: they’re more expensive than chlorine and you also have to buy additional chemicals to ensure a safe environment for pool users.

Pros and Cons of Using PHMB

Pros:

  • Completely chlorine-free pool water.
  • It kills microbe effectively.
  • It doesn’t cause skin and eye irritation.
  • It’s stable and won’t degrade with sunlight and changes in temperature.

Cons:

  • Relatively high maintenance costs.
  • You have to add an oxidizer (hydrogen peroxide) to break down contaminants and eliminate organic build-ups.
  • You should also add algaecide to the water.
  • It can cause foaming.

4. Mineral Sanitizers

Natural mineral sanitizers are getting popular: they’re effective, eco-friendly and easy to maintain.

There are two main types of mineral pool systems: mineral ionizers use electricity to create and feed metal ions (usually copper and silver) into the pool water that eliminate algae and kill bacteria, while erosion (or supplemental) type mineral sanitizers don’t need electricity, instead they contain a replaceable pre-filled cartridge full of natural minerals (usually sodium chloride, magnesium chloride, potassium chloride, and borates) that are being dispensed into the water gradually.

Both types of mineral pool water system need some additional chlorine (usually 0.5-1 ppm) because they can’t oxidize organic substances. Therefore, you have to test the water quality regularly (weekly or so) because you want TDS (total dissolved solids) to stay under 1000 ppm. Otherwise, your pool’s water becomes cloudy and may also have an unpleasant smell.

While electric mineral ionizers have a higher initial cost (and low maintenance costs), erosion type mineral sanitizers are pretty affordable: Nature2 and Frog products are highly popular and offer a reliable solution to lower the chlorine use.

Pros and Cons of Using a Mineral Sanitizer System

Pros:

  • It’s gentle on the skin and doesn’t cause any irritation.
  • Easy and inexpensive maintenance.
  • Eliminates both algae and bacteria.
  • You can lower the chlorine use up to 50%.
  • It helps keep the pH balanced.

Cons:

  • Electric mineral ionizers usually have a higher upfront cost.
  • Mineral pool systems can’t neutralize organic substances, thus you have to add some chlorine and test the water on a weekly basis.
  • Electric mineral ionizers can stain the surfaces of the pool when used improperly (this is not true for erosion type mineral sanitizers).

5. UV Light Purification System

UV (ultraviolet) light is a well-known and commonly used sanitizer in a wide range of industries. UV-C is a specific part of the whole ultraviolet spectrum that is responsible for the disinfecting effect. It’s capable of killing many different kinds of pathogens, including algae, bacteria, and viruses.

The idea that you can kill all the germs with light that’s harmless to humans without using any chemicals can be very appealing, however, UV light systems have their own drawbacks.

How does an ultraviolet light system work? The water coming from the pool’s filter passes through the UV system where it’s sanitized and then circulates out into the pool. The UV-C rays kill the pathogens by destroying their DNA or RNA (in the case of some viruses) so no chemical is needed for the process.

UV-C light is very effective, but it’s recommended that you also add some chlorine to the pool (0.3-0.5 ppm) because UV systems can’t oxidize water, thus they’re unable to remove organic debris (like dead cells) from the pool.

Pros and Cons of Using a UV Light System

Pros:

  • It effectively kills pathogens.
  • It’s eco-friendly, and it doesn’t produce any byproduct.
  • It works independently of the temperature and pH level.
  • It has no side-effects, and it doesn’t irritate your skin and eyes.
  • Requires very little maintenance.

Cons:

  • High upfront costs.
  • It’s not recommended using UV light in itself to purify pool water: you also have to add chlorine.

6. Salt Water Pool

Salt water sanitizing systems are growing in popularity and for a good reason: they keep your pool really clean without any hassle. If you’re looking for pool chlorine alternatives to avoid red eyes, itchy skin and “chlorine smell” then you may want to consider this solution. However, if reducing or completely eliminating chlorine from your pool (and not just some of its most unpleasant effects) is your main goal, then salt water sanitizing systems are not for you because salt pools are basically chlorine pools.

How does a salt water pool work? In a brief, it uses dissolved salt to generate chlorine molecules that form hypochlorous acid after reacting the water molecules.

All this happens with the help of a chlorine generator (aka salt cell) that uses a process called electrolysis to produce chlorine from the salt (if you want to dive into the chemistry of chlorine, check out this site).

So, you only have to add salt to your pool and the generator does the rest. A saltwater pool has about 10% of the salt level of the ocean, so the water has a very mild salt taste and it won’t hurt your eyes.

Why a salt water pool is better than adding chlorine directly to your pool? When chlorine reacts with organic substances chloramines are formed. The accumulation of these chloramine molecules is responsible for the most common adverse effects of a chlorine pool: skin and eye irritation and unpleasant “chlorine” odor.

A salt water sanitizing system continuously provides enough free chlorine that eliminates chloramines so it can’t accumulate. In contrast, if you add chlorine directly to your pool, you’ll have to shock your pool regularly (weekly or semi-weekly) to get rid of chloramines.

One major disadvantage of salt water chlorination is the initial cost. A chlorine generator usually cost $1500-$2500 (with installation) and the cell unit needs to be replaced after 4-7 years. On the other hand, it’s much cheaper to maintain a salt water pool ($50-$80/year) than a traditional chlorine pool ($250-$300/year).

Pros and Cons of a Salt Water Pool

Pros:

  • It provides powerful sanitation and soft, clear water.
  • No need for chlorine tablets.
  • It continuously eliminates chloramines from the water without having to shock the pool.
  • It reduces the risk of skin and eye irritation.
  • You will hardly feel any chlorine smell.
  • It’s very easy to maintain, however you have to test the water at least once a week.

Cons:

  • High initial cost.
  • You have to replace the salt cell unit regularly (every 4-7 years).
  • Salt being corrosive may damage certain metal equipment of the pool, especially if the water chemistry or the chlorine generator is not maintained properly. Also, salt water may harm nearby plants if they’re regularly exposed to it.
  • The pH usually rises rapidly in a salt water pool that you have to adjust regularly.
  • If you want to reduce or avoid all forms of chlorine in your pool, this solution is not meant for you.

Summary: Pool Chlorine Alternatives In a Nutshell

As you can see, there are many pool chlorine alternatives you can choose from if you want to invest in a new pool system. It’s important to always keep in mind your own priorities and the individual characteristics of your pool. Do you need a completely chlorine free pool or just want to reduce the amount of chlorine? Is easy maintenance crucial? Do you want to use the least amount of chemicals possible? Do you have an indoor or an outdoor pool? What’s your budget? There are many questions you should answer before you choose the solution that’s the most suitable for you.

In the last few years, mineral pool systems are getting more and more popular and if you don’t need a completely chlorine free pool (and don’t want to spend a fortune), they can be a great solution to keep your pool clean.

On the other hand, if your goal is a non-chlorine pool, you should consider PHMB, ozone purification (combined with bromine) or bromine (especially in hot water pools and spas) to substitute chlorine. Anyway, every pool is different, so when in doubt, don’t hesitate to ask for professional help.

As a side note, if you live in a climate where alligators are a real concern and want to know how you can keep them out of your pool (and yard), don’t miss our comprehensive article.

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James Mora is the founder of DailyHomeSafety. He is an avid DIYer, former healthcare professional and security manager. He is passionate about home improvement and teaching.