Ozone is safe to use with several popular alternative sanitizers, although there are a couple exceptions. In fact, a combination of ozone as the primary sanitizer with a small amount of a suitable alternative sanitizer to keep a residual in the hot tub at all times is our recommended method for hot tub sanitation.

A Summary of Ozone – Alternative Interactions

The following chart summarizes how ozone interacts with some popular alternative sanitizers.

Alternative Sanitizers Details

Every alternative has pros and cons.  We have looked at all of them closely, and here’s our summary of how each works as a sanitizer, especially as a secondary sanitation supplement to ozone.

Chlorine. This is the traditional foundation for most peoples’ hot tub sanitation routines.  Chlorine is a low-cost, well-known and widely available alternative that is a bactericide and a low-level oxidizer.  However, it must be maintained at the proper level (free available chlorine of about 2 ppm in hot tub water) to be effective, and it is easy for chlorine maintenance programs to get out of balance.  Using chlorine as a supplement to ozone by keeping a lower level of chlorine (about .5 to 1 ppm) in the hot tub will make the maintenance routine much simpler and more effective.

Bromine.  Bromine and ozone can interact to create bromates, a known carcinogen. WE do not recommend using bromine with ozone, except for use on residential spas.

*Biguanides.  Sometimes called PHMB, biguanides like Baquacil, Baqua-Spa and Soft Swim are popular alternatives to chlorine and bromine because they do kill bacteria without the chlorine smell and feel. However, they also cause foaming continuously, fail to oxidize organic matter in the spa (people usually use hydrogen peroxide in addition), and worst of all, over time use of biguanides is known to promote biguanide-resistant organisms.  We also recommend avoiding chlorine or bromine with this product.

Note that in the past some experts suggested that ozone could be used in conjunction with biguanides. More recently, others have indicated that ozone is incompatible with biguanides.  We recommend staying away from it because there are better alternatives available.

Minerals. Products like Nature2 and Frog introduce ions of copper, silver and/or zinc into the spa water. These bactericides and algaecides are effective alternatives to chlorine, and do not produce the negative effects of high chlorine concentrations. However, unlike ozone, they do not oxidize organic matter in the pool (lotions, makeup, perspiration, urine), so they need a supplementary oxidizer.  A sufficiently strong ozone system can serve as the primary sanitizer/oxidizer with these products, allowing the use of the minerals at a low level that will certainly avoid the side effects of minerals, including the staining caused by excess mineral concentrations.

Ionizers.  These are very similar in chemistry to the mineral products, except they introduce the copper and/or silver ions by means of electrolysis. They can be used in conjunction with ozone, but there are easier and more effective alternatives that avoid the electrical power drain to achieve the same ends.

Ozone is the Superior Spa Sanitizer

The broad-spectrum impact of spa ozonation in killing dangerous microorganisms, oxidizing organic waste, and reducing the need for chemicals cannot be beat. A properly sized and installed ozone generator should be the foundation of your spa or hot tub sanitation/oxidation program.