If you have the money and would prefer the convenience and peace of mind of an automatic sanitizer, here are a few options.
Chlorine and Bromine Generators. These electrical units create chlorine or bromine from special salts added to the water. Some units regenerate a bromine bank already in the water. Chlorine and bromine generators are great for maintaining a sanitizer residual, although periodic shocking is still required.
Ozonators. An ozonator produces and releases ozone, an effective sanitizer, into spa water. However, ozone doesn’t last long in a water environment. Once it kills bacteria,
the ozone reverts to oxygen and either dissolves into the water or escapes into the air. There is no easy way to ensure a sufficient ozone residual as new contaminants are introduced. Therefore, an ozonator must be used in conjunction with small amounts of a chemical sanitizer.
There are two types of ozonators: UV and corona discharge. A UV unit creates ozone with a special lightbulb, which needs to be replaced after many months. A corona discharge unit has a special cell that produces ozone. Corona discharge ozonators cost more than UV ozonators, but they don’t have any bulbs that need replacing.
Mineral Purifiers. These devices use a combination of silver, copper, and zinc to sanitize water. Some mineral purifiers are simply perforated cylinders that fit inside a spa’s cartridge filter, whereas others are plumbed in-line along with the spa’s other equipment. As water flows through the device and over the mineral bed, it picks up ions that kill bacteria. Such mineral purifiers last several months before they need replacing. Another type of mineral purifier is an ionizer, which is an electrical device that introduces silver, copper, and zinc ions into the water. Mineral purifiers, however, do not create a sanitizing residual, so they must be used in conjunction with a chemical sanitizer.