Chlorine Generators: These devices contain titanium plates with a special coating and generate chlorine from salt that was added to the pool water. After the chlorine is used it reverts back to salt to be reused. This device is really not an ‘alternative’ system, as free available chlorine (FAC) is produced and reacts the same as adding chlorine from a purchased bucket without the added byproducts that come with packaged chlorine and are dissolved in the water.

 Ionizers: These are usually copper and or silver electrodes which introduce soluble copper and or silver ions to the pool when an electric current is passed through the unit. Copper is used for algae control and silver for bacteria control. While once touted as “chlorine-free” systems, they are now mainly sold as devices to be used with low levels of chlorine. These ‘heavy metal’ devices (so-named because of the high density of elemental metals) are sold in the pool industry as ‘alternative’ sanitizers.

 They have several shortcomings, however. First, in Canada, silver is not allowed as a sanitizer and is not even allowed to be listed in any accompanying literature. Second, silver is relatively slow in its ability to sanitize. Third, although copper is an extremely effective algaecide, it has the propensity to precipitate and discolour pool surfaces with a tenacious stain. Finally, these devices are not oxidizers, so 90% of the workload of chlorine is not fulfilled.

 Magnets: Using magnets as water conditioners, mainly for pH and scale control, is possibly a scam. Aggressive marketing and threats of legal action often silence the opponents of magnetic devices. These devices are also sold as a way to increase gas mileage when attached to the gas tank and as a way to increase blood circulation when attached to the body by adhesive tape.

 Oxygen generators: These devices pass current between two electrodes resulting in the electrolysis of water creating two volumes of hydrogen at the cathode and one volume of oxygen at the anode. The word “nascent” oxygen is often used to give them a scientific flair. The sanitation properties of oxygen are flaunted. This weakly soluble oxygen has little – if any – ability to kill bacteria or oxidize organics and the failure of such systems was once the topic on the TV show ‘Hard Copy’.

 Ozone Generators: These create 0³ by passing air through either Corona Discharge (CD) or Ultraviolet (UV) Radiation. Ozone – an extremely powerful oxidizing agent – is so unstable that is must be generated at the point of entry into the pool. Due to its activity and low solubility, it does not leave a required residual past 22 minutes in the water and must be used with chlorine or bromine. It is not a stand-alone system. Allowing ozone to accumulate in enclosed areas can also compromise the health of the individual.

 UV Devices: It is known that bacteria are killed when subjected to certain wave lengths of ultraviolet light. You may have seen surgical instruments sterilized under UV light. Having UV irradiate water passing through a transparent pipe in the return line may kill the bacteria in the pipe, but it has no effect on sanitizing the remaining water in the pool. UV leaves no residual and no ability to oxidize. Trojan Technologies of London, Ontario, which sells UV generators, dismisses the use of UV technology for use in pools.

Oxidative Catalysts: These devices use a cartridge attached to the return line which contains metallic copper and finely divided elemental silver. There are no electrical components. The copper and silver dissolve by erosion or corrosion. Finely divided silver is known to be an oxidative catalyst in the synthesis of certain hydrocarbons. These devices claim that they can control algae and can assist chlorine in killing bacteria. This device is incompatible with bromine sanitizers. It has no ability to oxidize. While little staining occurs with copper, it is often difficult to measure any copper residual in the water. Some critics of this device say it is a form of homeopathy, a branch of medicine, which dilutes the drug to a point where it cannot be detected and yet claims medicinal results. Claims for silver efficacy are not allowed in Canada.