The 4 swimming pool system types are as follows:
Chlorine: Chlorine tabs or “shock” is introduced into the water in order to kill bio-threats in the water. This system is tied with salt systems as being the least healthy swimming option due to carcinogenic chlorine by-products. Cryptosporidium is highly immune to chlorine which is why cryto is the leading cause of waterborne illness every year.
Salt: Hundreds of pounds of salt are dissolved into the pool water and then the salt system converts the salt molecule into a chlorine molecule in order to kill bio-threats in the pool water. Salt systems save money on purchasing chlorine and shock but can cause very costly damage to the pool structure and equipment through the process of corrosion. Salt systems also can have carcinogenic by-products. Salt systems do not kill cryptosporidium.
AOP: Advanced Oxidation Process produces hydroxyl radicals which kill cryptosporidium on contact. Most standard AOP systems incorporate copper or silver ions to serve a residual sanitation effect in the water 24/7. These systems achieve a very healthy swim and are slightly less expensive than the AOP+ systems.
AOP+: This system is the same as the AOP system described above plus HET-UV (High Exposure Time Ultraviolet Light) and NSF-61 (Drinkable Standard) Certified Filtration. AOP+ is the healthiest way to swim by far and it reduces damage caused to the pool equipment and pool structure.