A hot tub Ozonator creates ozone in the water by splitting oxygen atoms into free oxygen atoms. These free oxygen atoms collide and combine with other oxygen atoms and create powerful oxidizers. These are said to reduce the need for chemical treatment of the water.
Is an Ozonator More Efficient?
In reality, an Ozonator is only effective when it is switched on and consuming electricity. The Ozonator should be on for at least 25% of the time or six hours a day. Once the Ozonator is not operating, the reduced level of sanitizers is faced with a normal level of contaminants.
Is it Worth it?
The reductions in the use of hot tub chemicals as a result of using an Ozonator are very impressive. If the reduction of the amount of these chemicals in your hot tub makes a significant difference to your enjoyment it is definitely worth it. Also, if you figure that the average price of an Ozonator is only about $100 versus about $75 for a chemical kit for your hot tub, you will see that an Ozonator will pay for itself rather quickly.
Is it Necessary?
This is a different question and might be answered by someone looking at the cost. An Ozonator running 6 hours a day costs more than using either bromine or chlorine. If cost is an issue and the chlorine or bromine are not issues then no, it is not necessary–just desirable.