Bromine vs Chlorine: A Sanitization Guide

Bromine vs Chlorine: A Sanitization Guide

Both bromine and chlorine are popular sanitizing agents that are extensively used to keep pool and spa water clean by eliminating bacteria. Although designed to perform the same role, these two compounds differ in their cleaning methodologies, temperature reactions, and skin. This guide seeks to assist you in choosing between bromine and chlorine based on your specific needs. 

Bromine vs. Chlorine: Understanding the Difference 

While both compounds work towards a common goal, their mechanisms of operation vary. 

Chlorine uses a chemical cleaning process known as oxidation. Adding chlorine to your pool or spa water steals electrons from pollutants, altering their molecular structure. The process leaves a byproduct called chloramine, responsible for the distinct chlorine smell and the skin-drying effects we associate with chlorine. 

On the other hand, bromine utilizes a process known as ionization, which forcibly separates the chemical bonds of the contaminants. Bromine has a lower pH than chlorine, which aids in balancing the water chemistry of your pool or spa. 

Here are some pros and cons of both chemicals, organized into categories: 

Physical Form 

Chlorine comes in various forms: sticks, tablets, and dry granular. Among these, tablets are favored due to their low-maintenance nature. Bromine, too, is available as tablets and granules, and it dissolves similarly to chlorine. 


The quantity of each chemical required to achieve the same sanitizing effect varies. As a general guideline, 

  • Chlorine: 1-3 ppm (parts per million) 
  • Bromine: 3-5 ppm (parts per million) 

Though you need more bromine to clean the same amount of water as chlorine, the frequency of chemical addition is less, balancing out the dosage over time. You may even use less bromine in total. 


Both chemicals successfully destroy contaminants, but their reaction rates differ. 

Chlorine acts faster to kill contaminants but dissipates quickly, resulting in a shorter period of effectiveness. Conversely, bromine operates more slowly but remains effective for a longer time. Its low pH helps keep the water chemistry balanced, reducing the need for chemical adjustments. 

Bromine is more stable than chlorine, particularly in warm water, making it the preferred choice for spas. Pools usually employ chlorine, although ultraviolet (UV) light can degrade both chemicals, with bromine breaking down faster. 


The cost is a significant point of difference between bromine and chlorine. Bromine can be up to twice as expensive as chlorine, so most pool owners opt for chlorine. The equipment required for bromine use, such as a floating feeder system, comes at a slightly higher price. 

Health & Safety 

Both bromine and chlorine are safe for human use when handled according to the manufacturers' instructions. Side effects are generally dependent on individual sensitivity to the chemicals. 

Chlorine can be harsh for sensitive skin, eyes, or respiratory conditions like asthma. Bromine is less abrasive, has a less chemical smell, and is less likely to trigger asthma attacks, making it a great alternative. However, bromine can leave a lingering odor that is harder to wash off than chlorine. Bromine is not a safe alternative for those allergic to chlorine, as it is still chlorine-based. 

Bromine vs. Chlorine: Making the Choice 

Both bromine and chlorine are highly effective sanitizers for pools and spas. Your choice between them should depend on your unique circumstances and personal preferences. 

Irrespective of your choice between chlorine and bromine, remember these critical safety rules: 

  • Never mix the chemicals in the water or their dry state, as this could trigger dangerous reactions 
  • Do not store the compounds next to each other due to the risk of combustible fumes 
  • Use a different feeder for both compounds, even after a thorough cleaning 
  • If switching from one sanitizer to another, perform a complete drain, clean, and line flush to avoid potential chemical reactions 


By understanding the characteristics, pros, and cons of bromine and chlorine, you can decide on the best sanitizing agent for your pool or spa.