Odd water chemistry behavior...

[ndabunka]

I decided to perform my end-of winter water change yesterday and something very odd occurred. I use di-chlor only and have both a regular test kit as well as some strips. The strips have a bromine reading section that has NEVER had any reading previously. This always made sense because I don't use Bromine. However, I have always had problems keeping my alkalinity levels in range and they were WAY high before this change. I drained the tub about 75% and then refilled. Got mostly normal readings afterward with one exception.... I now have Bromine level readings? How is this possible? Could Bromine possibly have come from the city's water supply? The one thing I did do was to get some more di-chlor form the local Lowes store. It seemed to be more "chunky" (i.e. less fine) than the prior di-chlor I had been using. At this point I assume the chemicals were packaged wrong and am planning on taking it back to the store for a replacement but this IS frustrating as it now appears that I have to once again fully drain the tub in order to get all the bromine out. I assume I have to pull EVERY bit of the existing water out now so that any Bromine remenants don't remain to be activated. Does this mean I also have to drain all water from the pumps during the drain with a wet-dry vac? I have one, so I could I just would rather not have to go through the re-priming effort if there is a way around it. Oh well, the tub has been facing one way for nearly 3 years now so maybe I'll re-orient the view while I've got it empty...

[leisure]

If you read a bottle of bromine ingredients you will notice that Bromine is chlorine based with lots of fillers.... It is ok as is you just have a high chlorine level....

[Soakin]

Sounds like you have identified the likely sources of the bromine, and I'd be leaning toward mislabeling/packaging, too, but I was wondering... is it possible that your test strips got contaminated (I think the bottles usually warn against reaching in), or that the bromine section is picking up a free or total chlorine reading?  If I remember correctly, my strips have a section for Total Chlorine, and one that reads Free Chlorine or Bromine, but no section for bromine alone.  I think my Taylor kit uses the same reagents for chlorine or bromine, so I don't know how a test strip would differentiate.

I also was wondering if your alkalinity problems could be affecting your readings (chlorine changes forms at high pH).  Are your alk and pH levels balanced now?

Just curious, if there is bromine in there why do you need to get it all out of the spa?  I am pretty sure you can shock a bromine tub with dichlor, so I don't see why they can't co-exist -- unless you have some allergies.

[Dr. Spa™ Ret.]

You don't have bromine in the water. And I'm VERY surprised you've never gotten a reading for bromine before!

Bromine test strips don't test for bromine, and chlorine test strips don't test for chlorine.

What the heck you ask? The test pads are impregnated with a chemical that changes color based on the "oxidizing potential" of the water. Chlorine has an "oxidizing potential", and so does bromine. Both of these substances, as well as quite a few others,  will cause the pads to change color.

"Bromine" test strips are calibrated to match up with a specific color chart that indicates how much bromine is in the water.

"Chlorine" test strips are calibrated to match up with a specific color chart that indicates how much chlorine is in the water.

Chlorine will change the color of a "bromine" pad, and visa versa, but because the calibration is specific to one sanitizer or the other, the color chart indicating the ppm will be off, way off.

So basically, chlorine will cause bromine test strips to change color, but the color chart for bromine test strips can't be used to accurately determine the actual amount of chlorine in the water (actually this isn't quite true as there is a formula you can use to make a conversion and figure it out).