The right pool sanitation system depends on what matters most to you: upfront cost, weekly upkeep, how the water feels, or how much chlorine you want to handle. Every system below still relies on a chlorine residual to keep pool water sanitized. What changes from one system to the next is how much chlorine the pool needs, how much work the system takes and how well it deals with chloramines and chlorine-resistant germs.
Do all pool sanitation systems still need chlorine?
Yes. CDC recommends at least 1 ppm free chlorine in pools (at least 2 ppm in pools that use chlorine stabilizer), at least 3 ppm in hot tubs and a pH of 7.0 to 7.8 (CDC, 2024). Salt water systems make their own chlorine. Hydroxyl-based AOP, ozone + UV AOP, UV and ozone are supplemental systems: they lower how much chlorine a pool needs, and the pool still keeps a low chlorine residual. CDC’s 2024 Model Aquatic Health Code puts it plainly for public pools: “A free chlorine residual must be maintained for adequate disinfection.”
What are the main types of pool sanitation systems?
There are six common options for home pools and spas. Two are chlorine-based: salt water systems and traditional chlorine. Four are supplemental systems that work alongside a low chlorine residual: hydroxyl-based AOP, ozone + UV AOP, UV and ozone. The table compares them on the same points.
| System | How it works | Chlorine still needed? | Equipment upkeep | Main watch-out |
|---|---|---|---|---|
| Traditional chlorine | Chlorine sanitizes, oxidizes and leaves a residual | Yes, chlorine is the sanitizer | Frequent testing and dosing | Chloramines that irritate eyes, skin and airways |
| Salt water | A salt cell turns dissolved salt into chlorine | Yes, the salt cell makes it | Salt cell cleaning and replacement | Salt can be hard on some surfaces and equipment |
| Hydroxyl-based AOP (Clear Comfort) | Hydroxyl radicals oxidize contaminants and chloramines | Yes, a low residual (typical 0.5 to 1.5 ppm) | Annual cartridge exchange, approximately 1 to 5 minutes per year | Still needs normal water balance and testing |
| Ozone + UV AOP | Ozone generator and UV lamp work together | Yes, a lower residual | UV lamp and ozone generator service | Ozone must be off-gassed |
| UV | UV light inactivates germs inside the chamber | Yes, UV leaves no residual | Lamp cleaning and replacement | Treats only the water passing through the chamber |
| Ozone | Ozone gas is injected as an oxidizer | Yes | Generator and off-gas equipment service | Ozone gas irritates airways |
How does a salt water pool system work?
A salt water pool is a chlorine pool. The salt chlorine generator, or salt cell, turns dissolved salt into chlorine, so the pool is sanitized by the same chemical as a traditional chlorine pool. Owners often choose salt water for the softer feel and because they no longer buy and add chlorine by hand. The tradeoffs are the cost of the generator, periodic salt cell cleaning and replacement, and salt water that can be hard on some surfaces and equipment. Our salt water pool systems guide covers the details, and salt water vs. Clear Comfort AOP compares the two directly.
How does a traditional chlorine pool system work?
Traditional chlorine is added as tablets, liquid or granules, and it sanitizes the water while leaving a residual that keeps working between treatments. Traditional chlorine is inexpensive and widely available. The downside is chloramines: when chlorine binds to sweat, urine and other body waste, it forms chloramines, which CDC says “irritate skin, eyes, and the respiratory tract” (CDC, 2025). The strong “pool smell” most people notice comes from chloramines. Learn more in what causes pool chlorine smell. Chlorine also works slowly on some germs: Cryptosporidium can survive more than 7 days at CDC-recommended chlorine levels (CDC MMWR, 2019).
What is a hydroxyl-based AOP pool system?
A hydroxyl-based AOP (advanced oxidation process) system draws in air, treats it and injects it into the pool’s plumbing, where it creates hydroxyl radicals. Hydroxyl radicals are short-lived oxidizers that break down organic contaminants and chloramines. Clear Comfort’s hydroxyl-based AOP is a patented technology, and you can read how it works on our AOP technology page or in what is a hydroxyl radical.
With hydroxyl-based AOP, typical free chlorine in a residential pool is 0.5 to 1.5 ppm. Maintenance is an annual cartridge exchange that takes approximately 1 to 5 minutes per year. In a 2014 University of Colorado Boulder lab study, the Clear Comfort system achieved up to 99.99% (4-log) inactivation of chlorine-resistant Cryptosporidium within 60 minutes under test conditions (Linden Research Group, 2014). A hydroxyl-based AOP pool still needs a low chlorine residual, regular testing, balanced water, circulation and cleaning.
How is ozone + UV AOP different from hydroxyl-based AOP?
Ozone + UV AOP combines an ozone generator with a UV lamp so that the two together create some hydroxyl radicals. Ozone + UV AOP systems have more parts to maintain (a UV lamp and an ozone generator) and need a way to off-gas ozone from the water. Hydroxyl-based AOP creates hydroxyl radicals directly and has one cartridge to exchange each year. Our AOP pool system guide compares the two in more detail.
Do UV pool systems work?
Yes, within limits. UV light inactivates germs, including Cryptosporidium, as water passes through the UV chamber; CDC notes that ultraviolet light and ozone “have been found to be effective against oocysts” (CDC MMWR, 2021). UV also breaks down chloramines in the water that passes the lamp (CDC, 2025). A UV system only treats water inside the chamber and leaves no residual in the pool, so the pool still needs chlorine. UV lamps need regular cleaning and periodic replacement. See UV vs. hydroxyl-based AOP for a side-by-side look.
Are ozone pool systems safe?
Ozone pool systems are used safely when they are installed and maintained correctly. An ozone system converts oxygen into ozone, a strong oxidizer that is injected into the water and can reduce how much chlorine a pool needs. Ozone gas is also a lung irritant: EPA describes ozone as “a powerful oxidant that can irritate the airways” (EPA, 2026). That is why ozone systems need a way to remove excess ozone before it can off-gas near swimmers, and why equipment rooms need ventilation.
Which pool sanitation system needs the least maintenance?
Hydroxyl-based AOP needs the least equipment upkeep of the six: one annual cartridge exchange that takes approximately 1 to 5 minutes per year. Salt water systems need salt cell cleaning and eventual replacement. UV and ozone systems need lamp, sleeve or generator service. Traditional chlorine needs the most hands-on dosing. No system removes routine pool care: every pool still needs testing, balanced pH, circulation, filtration and cleaning. For water balance, see how to balance pool pH, and for dosing, see how much chlorine to add to a pool.
How do you choose the right pool system?
Start with what you want to change. If upfront cost matters most, traditional chlorine is the least expensive to start. If you want to stop buying and adding chlorine by hand, a salt water system automates chlorine production. If you want to use less chlorine, cut down on chloramines and spend less time on equipment, a supplemental system such as hydroxyl-based AOP is worth a look. Then ask a local pool professional about your pool size, surfaces, equipment and how often the pool is used.
Frequently asked questions
Is a salt water pool chlorine-free?
No. A salt water pool is a chlorine pool. The salt chlorine generator converts dissolved salt into chlorine, and that chlorine sanitizes the water the same way added chlorine does.
Can I use a hydroxyl-based AOP system with a salt water pool?
Yes. A Clear Comfort hydroxyl-based AOP system can be installed alongside a salt chlorine generator. The salt system supplies the low chlorine residual, and the AOP system handles oxidation.
How much chlorine does a pool with hydroxyl-based AOP need?
With Clear Comfort hydroxyl-based AOP, typical free chlorine in a residential pool is 0.5 to 1.5 ppm. Your dealer will set the target for your pool, and the pool still needs a low chlorine residual at all times.
What is the lowest-maintenance pool sanitation system?
Hydroxyl-based AOP has the lowest equipment upkeep of the common systems: an annual cartridge exchange that takes approximately 1 to 5 minutes per year. Every pool, whatever the system, still needs regular testing, water balance, circulation and cleaning.
Does UV kill Cryptosporidium in a pool?
UV light inactivates Cryptosporidium as water passes through the UV chamber, and CDC reports that UV and ozone are effective against Cryptosporidium oocysts. UV leaves no residual in the pool, so a chlorine residual is still needed.
Do pool sanitation systems remove the need to test water?
No. Every pool sanitation system still needs regular water testing. CDC recommends keeping pH between 7.0 and 7.8 and free chlorine at or above the minimum for your pool or hot tub.
Ready to compare options for your pool? Find a Clear Comfort dealer near you.
