Alternatives To Chlorine For Your Pool

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Chlorine has been a popular water treatment for decades. It's inexpensive and effective at killing bacteria and controlling algae growth. For pool use specifically, it also neutralizes some of the negative effects of releasing body oils and perspiration into the water. Before you start thinking chlorine is the perfect additive, consider some of the potential downsides.

The Trouble With Chlorine

Chlorine can be irritating -- literally. It causes red, itchy eyes and other allergic reactions. It also smells nasty long after your skin has been exposed to it. It's drying to the hair and skin, and can cause treated hair to discolor.

As if that wasn't enough, chlorine has been potentially linked to serious medical conditions involving the bladder, colon, lungs and reproductive system. Chlorine may not be causing the biggest part of the problem, though. The culprits may actually be the chemical compounds produced when chlorine reacts to organic substances in water like sweat and urine. These chemicals include:

  • Aldehydes
  • Chloramines
  • Chloroform
  • Halogenated hydrocarbons
  • Nitrogen trichloride
  • Trihalomethanes

The body of evidence pointing a warning finger at the casual use of chlorine is growing and the hunt is on for a successful alternative that will eliminate the need for chlorine in pool water. To date, no single solution stands out as a perfect substitute for chlorine. Most work in concert with a reduced amount of chlorine. The obstacle is that chlorine:

  • kills bacteria
  • kills algae
  • and oxidizes organic material

Those are the big three when it comes to pool cleaning. Most of the alternatives only do two of the three tasks well and rely on chlorine or another additive, like concentrated hydrogen peroxide, to do the third.

Let's take a look at a few of the likely contenders that will keep your pool water safe, clear and clean smelling without -- or with less -- chlorine.


The acronym above refers to polyhexamethylene biguanide, a powerful anti-bacterial agent (or bactericide). Beyond killing bacteria, it's gentle on synthetic surfaces like PVC and pool lining material. It's odorless, too.

PHNB isn't effective at killing algae, though and it won't neutralize (oxidize) organic compounds like oil from your hair and skin, either. In the pool, it produces a heavy gel of spent bacteria to be vacuumed up off the bottom. A season's worth of product will cost $1,000 or more, and you'll still have to invest in an algaecide as well as a concentrated hydrogen peroxide product or other oxidizer. PHNB may not be a good long term alternative, either. Bacteria tend to develop a resistance to it over time.


An ozonator introduces ozone gas to the water, killing bacteria in the process. Ozone is an effective sanitizer and also oxidizes biological material. In your pool, the gas is produced and deployed via a machine attached to the filtration system. That means the filter has to be running continuously for an ozonator to work efficiently.

There are basically two types of ozonators to choose from: UV lights (common in hot tubs), and corona discharge technology. Both are available for backyard pool installations in the $1,200 range. Ozone equipment is economical to use, and under optimum conditions can reduce dependence on chlorine by 90 percent or more.


Ionizers work by using low-voltage current to release microscopic metal particles into the water that attract bacteria. The metal (usually a combination of copper and silver) works to control bacteria and algae, which is then flushed out of the pool via the filter system. Exposure to the metal is safe for humans. The technology has been around a while. Actually, silver impregnated water filter media is very popular for its ability to control bacteria in drinking water. Ionizers work best with some onboard chlorine as an oxidizing agent. Ionizers are odorless and chemically benign. They can reduce dependence on chlorine by more than half.


For the 5 percent of people allergic to chlorine, bromine is the popular alternative. It sanitizes, but isn't as effective at algae control or for oxidizing organic compounds as chlorine. That's why the most popular bromine products on the market are a blend of chlorine and bromine or a two-step application of bromine salts and potassium peroxymonosulfate. Even at that, you'll definitely notice the green color of a bromine rich solution. Bromine also tends to create suds and foam when the pool water is agitated.

For products that blend bromine and chlorine, the ratios vary from brand to brand, but will usually be made up of 65 percent bromine or so with the rest coming from chlorine and minor ingredients. Bromine has some of the disadvantages of chlorine in that it can be mildly irritating (but somewhat less so than chlorine), and it smells strong and vaguely of chlorine (they're actually related chemically).

Because the alternatives to chlorine can be challenging to use, if you opt for one of them, be sure to test your pool water often and make frequent, small adjustments.

For more information on the health impact of using chlorine, see Health Effects Of Chlorine In Swimming Pools.

Last Updated: September 9, 2012
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About Sara Elliot Sara Elliott is a freelance copywriter and dedicated blogger. Her popular gardening, cooking and crafting blog, The Herb Gardener, was cited by The Wall Street Journal for its fun and frugal tips. Sara has a degree in English, and you can find her health, crafting, and lifestyle pieces on sites like,, and

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