Can you replace chlorine usage in a swimming pool when you use ozone?

Answer 1

Not really.

Most disease transmission in pools is swimmer to water to swimmer. The disease carrying organisms never go through the filter system before infecting another swimmer. Consequently, an adequate pool sanitizer must be present where the germs are, out in the pool.

Chlorine, bromine, PHMB (Baquacil, etc) all meet this requirement. Chlorine is by far the fastest acting and most effective sanitizer, but all three meet the minimum requirement of providing sanitation where the germs meet the people.

By contrast, ozone does not. Unlike chlorine gas, ozone gas is not very water soluble. And -- though it surprises most people -- ozone gas is considerably more toxic, if inhaled, than chlorine gas. Consequently, ozone systems must be designed so that no undissolved ozone gas reaches the pool, where it could escape and endanger swimmers. In Europe, where commercial pool ozone systems are sometimes very high capacity, an ozone removal stage is added to the filtration system. But, in the US, the problem is usually solved by making sure the ozone system is so small, that no ozone can ever remain in the water that's returned to the pool.

Either way, ozone is never present in water that's in the pool; it's only present in water that's in the pipes.

Consequently, ozone systems can never provide primary sanitation, protecting swimmers out in the pool, where the germs are.