Test kit for bromine

grottoguy

LifeTime Supporter
Aug 24, 2014
462
NJ
I have a stand alone hot tub that uses Bromine and I have the TFT100 test kit, which can test for bromine. But is the Taylor 2106 a more precise Bromine test. Do you recommend that over the TFT100 test for this purpose.
 

JVTrain

TFP Expert
Feb 3, 2014
5,081
Central Minnesota
The K-2106 has the EXACT same test as the FAS-DPD test included with your TF-100.

In the 25 mL sample size, 1 drop = 0.5 ppm Bromine
In the 10 mL sample size, 1 drop = 1.25 ppm Bromine.
 

grottoguy

LifeTime Supporter
Aug 24, 2014
462
NJ
Joel,

I don't follow. My TF-100 seems to only have one bromine test, and that is the color comparison test in the PH/Chlorine Taylor test. The K-2106 seems to have a powder Bromine test. My question was whether it made sense for me to get k-2106 bromine test or just stick with the TFT-100.
 

JVTrain

TFP Expert
Feb 3, 2014
5,081
Central Minnesota
The FAS-DPD test included with your TF-100 measures BOTH FC and Bromine. It the exact same reagents as the test included with the K-2106. You have to know if your pool or spa is bromine or chlorine but the test is the same.

Using a 10 mL sample, add a heaping scoop of the DPD powder, then dropwise add R-0871 until clear. If you have a bromine pool/spa, multiply the drops result by 1.25 to get your Bromine concentration. If you have a chlorine pool/spa, multiply the drops result by 0.5 to give your FC concentration. Using a 25 mL sample, you multiply the drops by 0.5 for Bromine and 0.2 for FC.

The K-1000 test block included with your TF-100 will also give you a Bromine concentration below ~10 ppm as a color match.
 

grottoguy

LifeTime Supporter
Aug 24, 2014
462
NJ
Thanks a lot. The TFT directions don't mention that. I'm going to suggest to Rebecca she include that information.
 

grottoguy

LifeTime Supporter
Aug 24, 2014
462
NJ
Joel,

The Taylor website seems to say that the k-2106 is only for Bromine. That seemed strange if our test in the TFT100 could be used for both Chlorine and Bromine. Also, the Taylor test says we need to use r0872 but you indicated above that we use R0871. Sorry for bringing this up again, but are you sure you are correct?
 

welbo

Well-known member
Apr 14, 2016
81
College Station, TX
I bought a bottle of R-0872 to go with my K2006C kit in order to test specifically for Bromine, having the same thoughts as OP. After I learned that either will test for FC AND bromine, I just left the R-0872 in the kit. Out of curiosity one day I repeated a FAS/DPD test in my pool water using 10 mL samples, one with R-0871 and one with R-0872. It took 19 drops of R-0871 and 15 drops of R-0872 to achieve color change. That led me to believe there is a concentration difference between them. The difference seemed too much to be a margin of error.
I started a SLAM on the pool and didn't want to use up any more powder until my replacement comes in or I would have tried it again. I've seen those MSDS sheets before but don't know how to read them exactly and thought I may have missed something about concentrations. You sound pretty confident so I'll go with it being my error and try it again when the replacements come in. If it is my error, I'm a little worried about the accuracy I'm getting from my test. The directions are pretty clear and I don't THINK I was doing anything wrong.
What are some common mistakes that would cause that much error? The exact amount of powder isn't critical is it? The little scoops would have some variation and I'm not super careful when adding the two scoops.
 

JVTrain

TFP Expert
Feb 3, 2014
5,081
Central Minnesota
If using the R-0871 you would use a ratio of 2.25 x FC result to get your bromine concentration. This is simply because the same reaction is taking place but the molecular weight of bromine is about 2.25 times greater than chlorine. So... if you counted 19 drops of R-0871, that would be 19 x 0.5 x 2.25 = 21.375 bromine. With your R-0872, 15 drops would be 18.75 bromine based on the instructions. This is a significant difference in results.

The amount of powder is not critical, as long as their isn't too little. You essentially are saturating the solution with the R-0870 powder. Too much is not bad, too little is. Two level scoops or one heaped scoop is plenty, accuracy is not all that important as long as there is enough. An indicator that you know you have enough R-0870 is that there are a few crystals, particles of the powder floating in the solution as you have started to swirl/mix the solution. I have found that using a Speed Stir gives me more consistent results from test to test over hand swirling.

What I would do is contact Taylor directly and ask them what the difference is between the R-0871 and R-0872. Then you can address the problem as a difference in the two solutions or an issue with testing consistency.
 

welbo

Well-known member
Apr 14, 2016
81
College Station, TX
I did the test again this morning on my pool water. Again 10mL samples. 35 drops r-0871, 36 drops r-0872. So I must have done something wrong the last time I tried to compare them. My speedstir will be here today or tomorrow. I think that will help too.