Difference between Chlorine and Bromine test kit

[Smorgasbord]

First post on this forum, so let me just briefly say that I'm really grateful that this exists. You guys are awesome! It was a real struggle to find reliable information before finding this forum.

Now, as I'm starting out, I made a rookie mistake. I currently use bromine in my hot tub, and would like to keep it that way. However, I bought the test kit Taylor k-2006, which is meant for chlorine. My main question: do I really need to buy another test kit for Bromine now?

If you can help, I'd like to understand the difference between the FAS-DPD test for chlorine and for bromine. Taylor names the pure FAS-DPD tests K-1515-A,C for chlorine and K-1517-A,C for bromine. Different names; does that mean they are different chemicals? If I use my current chlorine test with the water containing bromine, what is it measuring? Does it really measure only the chlorine (free and combined) in the water? Or does it measure a combination of bromine and chlorine? The readings I get certainly seem high for just purely chlorine.

Many thanks!

[Osric]

I recently bought a K-2106 kit which is supposed to be the bromine kit, but it had the wrong reagent in it - R-0871 instead of R-0872. So I basically had the same problem you had, and I can confirm that the only difference seems to be the amount of bromine per drop when you do the Chlorine test. The conversion is:

Sample ml	Chlorine/drop	Bromine/drop
10	0.5	1.125
25	0.200	0.450
44	0.114	0.256

So you can follow the directions for the Chlorine test, but use the units above instead of what's printed in your test kit. 

I am not familiar with the other test kits you list, but I would assume that the bromine one contains R-0872 and the chlorine one contains R-0871. The photo for 1515A suggests that. 1515C looks like the identical kit with 2oz bottles of reagent instead of 0.75oz. The pricing of these kits is so similar that I'd get the smaller supplies of reagents as there's essentially no savings to the bigger bottles. Shelf life concerns would make me worry I couldn't use the 2oz bottles fast enough.

The photo for 1517A also matches my expectation - the difference being it contains the R-0872 reagent. 

I think the bottom line is you can do what you need with the test kit you bought, and you have a bunch of extra chemicals you will never need or use.

 

 

[Smorgasbord]

Thanks, Osric! This really answers my question. 

Do you know if there's still a way to measure  the amount of chloramines? 

[Osric]

Sorry I don't know what the role of chloramines is in a bromine tub, and I'm not even clear if they can build up in a bromine spa or not. You need someone better versed in the chemistry!

Based on my near-total lack of knowledge, I didn't think chloramines would build up/occur in your bromine tub. I thought that even if you shock the pool with Chlorine, what that does is bind to the organics and get filtered out by the filtration system, leaving the bromides reactivated as bromine to sanitize for the next week.

 

[Smorgasbord]

No problem, your answer was very helpful.