Bromine Testing

[bradw]

I have a Hach Chlorine Colorimeter digital test kit. Is there a conversion for bromine when done with a chlorine test? I have free and total chlorine reagents that came with the kit. Which one would be better? Thanks.

[chem geek]

The Bromine ppm is 2.25 times the Chlorine ppm though most test kits just show a factor of 2 difference. So, a 3 ppm chlorine measurement is 6 ppm Bromine, approximately (and it's 6.75 ppm, more accurately). Bromine is not quite as effective as chlorine in terms of sanitation, however, but since there is no CYA effect reducing it's effective concentration (though using BCDMH has some effect similar to CYA), you end up with much higher bromine concentration in the water than typical disinfecting chlorine. Unfortunately, I can't find much info on specific kill times when using bromine, especially for the bacteria that causes hot tub itch.

You use the normal reagents for the Free Chlorine test in checking Bromine (in the Taylor kit this is the R-0001 and R-0002 reagents). This technically tests Total Bromine due to the chemical nature of the test since bromine doesn't "stick" to other chemicals the way that chlorine does so any combined bromine gets "unstuck" even during the Free Chlorine type of test. Also, combined bromine chemicals are still effective sanitizers so the distinction between Free and Combined for Bromine isn't relevant. Bromine combines with ammonia to form bromamines which are still effective sanitizers (unlike the chlorine+ammonia chloramine compounds that are much weaker).

Richard

[bradw]

Thank you!

[waterbear]

You use the normal reagents for the Free Chlorine test in checking Bromine (in the Taylor kit this is the R-0001 and R-0002 reagents). This technically tests Total Bromine due to the chemical nature of the test since bromine doesn't "stick" to other chemicals the way that chlorine does so any combined bromine gets "unstuck" even during the Free Chlorine type of test. Also, combined bromine chemicals are still effective sanitizers so the distinction between Free and Combined for Bromine isn't relevant. Bromine combines with ammonia to form bromamines which are still effective sanitizers (unlike the chlorine+ammonia chloramine compounds that are much weaker).

Richard

Not entirely true. While bromamines are considered to be effective santizers they do contribute to the 'bromine smell' that many find offensive. This is one reason that regular shocking of a bromine system is important. It reduces the organic load and helps prevent the formation of bromamines.

Also, when testing bromine it is the Total Bromine that we measure, which is often a bit higher than the free bromine.The difference is usually small enough to be ignored, however, which is why free bromine is what is usually tested with DPD. You can actually just test for chlorine and if the readings are correct for chlorine you are going to be in the right ballpark for bromine levels. (For example, if your test kit shows 3 ppm chlorine you actually will have a bit over 6 ppm bromine.)