All hot tubs require spa chemicals called sanitizers to keep the water fresh and clean. However, which sanitizer you use – chlorine, bromine or biguanide – will depend on your needs and preference.

Differing Spa Sanitizers 

Before you add any sanitizing agent to your spa, first test the current levels of spa chemicals with a test strip. Test strips measure the level of bromine, chlorine or biguanide in your hot tub water as well as mineral content, and pH and calcium levels.

The most widely used spa sanitizer – chlorine – is the one most people are familiar with because it is the primary sanitizer used in swimming pools. Chlorine for hot tubs comes in tablet and granular form.

Bromine is often favored over chlorine because it produces fewer odors over its more familiar counterpart. It comes in tablet, nugget or granular form, which you distribute using a feeder or cartridge system.

Finally, biguanide (bi-gwan-eyed) is a non-chlorine, non-bromine product. You know that chlorine smell that you so often notice when hot tubbing? Well, because biguanide uses a hydrogen peroxide-based oxidizer to eliminate organic matter, it releases the fewest odors of all the spa sanitizers.

Using Spa Sanitizers

First, always follow the package instructions when using test strips and sanitizers. Next, keep in mind that all sanitizers require constant monitoring to keep the pH balanced. Finally, it is important to understand the advantages and disadvantages of using the various sanitizing spa chemicals.

Though chlorine tends to be the sanitizer of choice by many spa owners, it has the strongest odor. However, because of its popularity it is inexpensive and readily available. Keep in mind that when “free” chlorine – chlorine in its initial form – kills bacteria and oxidizes contaminants, it loses its sanitizing ability.

Bromine, on the other hand, still has sanitizing ability even when it combines with contaminants. In addition, it tends to be more stable in heat and turbulence, so it doesn’t “gas off” – lose carbon dioxide (CO2) – at high temperatures. Lost CO2 changes the pH balance. Though it has a milder odor than chlorine, it is not odorless. Unfortunately, it can dry skin and degrades in sunlight.

Biguanide produces the fewest odors and doesn’t gas off. However, some suggest that it may erode certain plastics and cause algae slime that is difficult to eliminate.

Choosing the right spa chemicals for your hot tub is all about balancing ease of use with effectiveness and preference. Do your research, weigh your options and be sure to ask questions.

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