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Technical Bulletin: Total Bromine - What are you Testing?
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Joe Sweazy, Environmental Test Systems, Inc.
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One of the most popular pool and spa sanitizers used today is bromine. Both the free and combined forms of bromine sanitize the water and help keep it clean and clear. It is important to measure free and combined bromine when testing the sanitizer level in a pool or spa. They are both effective.
How Bromine Works
Bromine may be introduced to the pool or spa in two different ways. A granular bromide salt (sodium bromide) can be added to the water, which is activated or converted to free bromine by a separate oxidizer. A second option is a compound of bromine that already contains oxidizer, most commonly available in “tablet” form. Regardless of the method, the desired effect is the same, to create free available bromine. The oxidized bromine forms hypobromous acid and hypobromite ions, both of which make up the free available bromine content. The hypobromous acid is the active form of bromine responsible for killing bacteria, algae and pathogenic organisms and it is also the predominant species present under normal pool and spa conditions. The hypobromite ions are relatively inactive.
Bromine then combines with contaminants in the water to form combined bromine (bromamines). The advantage of the bromine chemical is that this form, combined bromine, is also an effective sanitizer. This means that combined bromine can also kill bacteria. This is an advantage that distinguishes bromine from chlorine. While the same chemical reactions happen with chlorine, the combined form of chlorine (chloramines) is not nearly as effective a sanitizer.
Total Bromine
Total bromine is the combination of both free and combined bromine. Adding the amount of free bromine to the amount of combined bromine present in the water will give you the concentration of total bromine. Because both free and combined bromine compounds are effective sanitizers, this is the form of bromine that should be tested in order to determine the appropriate level of sanitation. An ideal level of total bromine is 3 to 5 ppm for pools and 4 to 6 ppm for spas. The minimum acceptable level is 2 ppm and the maximum allowable is 10 ppm according to NSPI standards.
Testing Total Bromine
There are many bromine tests available to the pool and spa industry. It is desirable to test for total bromine in order to get a true water analysis. It is best to use a test kit specifically labeled for bromine testing, not a combination of chlorine and bromine. A total bromine test is optimized to test all forms of bromine that would make up the sanitizer content. Tests that measure both chlorine and bromine are optimized for testing chlorine. In addition, some tests measure free chlorine and bromine. Doing this, testing free chlorine and multiplying by the factor of 2.25 (because bromine is 2.25 times heavier) will only give you a free bromine reading. This type of test does not take combined bromine into consideration, which as mentioned earlier, is an effective sanitizer.
AquaChekTM Red for total bromine measures all forms of sanitizing bromine accurately. This test is capable of reading both free and combined bromine, thus giving a true bromine sanitizer reading. In addition, AquaChek Red is ideal for testing in reference to the updated NSPI standards as color blocks are provided at key levels to help determine that ideal levels of bromine are being maintained.
© 2001
For information or a copy of this technical report call toll free 1-888-AQUACHEK™ (1-888-278-2243). Visit our website at www.Aquachek.com.
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