What is ozone? Ozone is a form of oxygen. The oxygen in the air we breathe is known as O2, ozone as O3.
How does ozone affect the water in my spa? O3 is an unstable molecule, meaning that one of the three oxygen atoms that makes it up wants to separate and attach itself to some other molecule. That rogue atom hooks up to the stuff you don't want in your spa's water, like bacteria and viruses. The bad stuff is destroyed, and all that's left is...oxygen!
Will I still need to use sanitizer if I have an ozonator? Sanitizers like Bromine and Biguanide will always be necessary, since the one thing ozone can't help you with is algae. However, you'll need to use a whole lot less of these chemicals, which, in high concentrations, can irritate your skin and eyes, plus damage your spa's surface and cover over time.