One additional application of ultraviolet radiation (UV) — and a potential complement to a UV system — is ozone.
While many ozone generators use a corona discharge (CD) unit to create this disinfecting gas, others use UV to split oxygen molecules (O2) into individual oxygen atoms (O), which then join into ozone (O3) molecules.
UV and UV-generated ozone are often paired for extra disinfection power — especially in places like Europe and Australia, where many cities impose limits on the levels of hazardous chemicals a pool can contain.
When combined with chlorine generated electrolytically from salt water on-site, options like this can provide comprehensive disinfection and sanitation systems that eliminate the need for regular chemical dosing and storage.
The main downside of a setup like this is the lack of ability to superchlorinate or shock the water in case of a contamination accident.
In such a case, the only option is to clear the pool of bathers, then manually add chlorine to the water until its concentration is 10 times normal. Once the water is sanitized, the remaining chloramines can be filtered and diluted out, and the pool can return to business as usual.