There are many different types of saltwater chlorinators or chlorine generators on the market today that can self generate chlorine by the addition of regular table salt to the pool water. It sounds kind of funny but really the amount of salt that is needed for this type of system to properly function is in the range of 2800 ppm to 4000 ppm of salt in the water. Now to get a grasp of how much salt that is, a teaspoon of salt in an 12 oz glass of water is somewhere within the required range, about 3000 ppm. I suggest doing this and tasting the water for yourself. Most people can barley notice a difference in taste. Salt also adds a more subtle benefit to the pool water by making "soft", similar to that of a water softener. This is much more beneficial to the skin than the harsh residue of normal chlorine. The process by which the chlorine is produced in by the electronic turbo cell as the salt water passes over the fins produces a byproduct of ozone that also is a natural sanitizer. There are just a handful of systems on the market today but the top two in my opinion are the Aquarite by Goldline and the Clearwater LM series from Zodiac. This type of system is the one I have on my own pool and swear by it. It is easy to maintain and only requires an occasional addition of salt annually due to overflow from rain fall.
Passive sanitizers such as the Frog system or Nature 2 are replaceable mineral cartridge systems that purify the pool water as it passes through them. These type of sanitizers are very effective with only one draw back in my opinion. They need a topical amount of chlorine to work properly. This means you still need to add a harsh chemical to the pool water however in a drastically reduced amount. The very apparent feature of this type system is that the water smells and feels like clean fresh rain water. This type of sanitizer is very commonly used in spas and hot tubs because of their ability to keep up with sanitary needs of the water and can be used with chlorine as well as bromine. Getting in a hot tub that has a harsh chlorine odor is less than appealing. In my opinion fresh rain water that sounds more like it.
Ozonators are one of the oldest types of alternative sanitizers used in the hot tub and personal spa industry because with small amounts of water the Ultra violet light unites could maintain a proper level of stability to the prevention of bacteria growth. With the advent of the new corona discharge models swimming pools can now benefit from this technology. Let me say first that with ozone sanitization you need ether ozone and chlorine or lots of ozone alone. Now most spas and hot tubs use ozone in addition to bromine, but what about pools? Well chlorine has to be used. We can't seem to get away from it unless we super size our ozonator. It is possible to do this now with the new 24hr ozonators from Del Ozone, however you must have decided on this before you built your pool because it requires additional in-floor plumbing to be the most effective. Other models will work for existing pools but remember size matters, the bigger the better when it comes to ozonators.
So where does that leave us? In my opinion of all these alternative sanitizers, I would choose first a salt system, then it's a toss up between a Nature 2 system passive and a ozone system, which by the way can be combined together to produce an even more effective passive/ozone means of sanitation.
