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High Bromine Levels


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#1 barnsley_teaher

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Posted 12 September 2012 - 11:52 AM

Can anyone help (waterbear). Have really high (well above 10ppm) bromine levels and have done for couple of days now despite no floater with tabs in tub for this period. The tub is not being used during week, weekends mainly so could be why bromine is not being used up but with no floater in with tabs thought it would fall but isn't doing. could ozonator be keeping levels high by oxidizing bromide.?
Also ph is really high above 8.4 and TA really low, below 40 and cant seem to stabalise. Add dry acid and falls for couple of hours but then next day high again. Please help this new hot tub owner......

#2 chem geek

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Posted 12 September 2012 - 05:16 PM

Absolutely it's your ozonator which is oxidizing bromide to bromine. That is normal after you've built up a bromide bank and have an ozonator. If you can turn off how long your ozonator runs, that will help.

That's a bit strange that you can't have your pH stay lower with such a low TA level. Perhaps your ozonator is on so much that it is aerating the water a lot. Again, turning down your ozonator on-time should help. You could also add 50 ppm Borates to the water to slow the rate of pH rise.

#3 waterbear

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Posted 12 September 2012 - 10:07 PM

The pH is not high. In fact I suspect it is dangerously low right now from all the dry acid additions. How are you testing your water first of all?
Now for a little chemistry lesson. HIgh sanitizer levels (either chlorine or bromine) will cause a chemical interference with the phenol red indicator used to test for pH and cause it to read high when it is not. Depending on the test kit or strips the can occur at chlorine or bromine levels as low as 3 ppm but in better kits such as the ones from Taylor are good up to about 10 ppm. You did not state how high your bromine was, just that it was above 10 ppm which leads me to believe that you are testing with strip and you do not have a Taylor K-2106 for bromine ( or a K-2006 for chlorine) because you would have posted just how much higher it was because these kits can read levels up t around 50 ppm.
So you have high bromine and it is converting the phenol red indicator for pH into bromophenol red and bromophenol blue indicators which have a similar color change but at a much lower pH level. Your pH test is turning a deep red purple color, is it not? All this tells you is that your pH is somewhere in the range of 4-6 to 6.8 or higher. However it can be as low as 4.6 and still produce this color! For the color to change to what appears to be a 'normal' pH (such as around 7.6) it means the pH is below 4.6! Are you following what i am saying?

The fact that your TA is around 40 ppm is good indication that your pH has "crashed".
I've tested more water than I ever care to think about!
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#4 chem geek

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Posted 13 September 2012 - 07:58 AM

Good catch waterbear. I missed the part about his bromine level being very high. With a TA of 40 ppm his pH can't crash all the way to 4.5, but if he started with normal pH and 80 ppm TA and kept adding acid his pH could be as low as 6.3 though carbon dioxide outgassing probably keeps it higher than that. According to Taylor, the chlorphenol red is dark purple when the actual pH is above 6.6:

FALSE READINGS: high levels of chlorine (usually > 10 ppm) will quickly and completely convert phenol red into another pH indicator (chlorphenol red). This new indicator is a dark purple when the water's pH is above 6.6. Unfortunately, some pool operators mistake the purple color for dark red and think the pool water is very alkaline and wrongly add acid to the pool.



#5 barnsley_teaher

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Posted 13 September 2012 - 08:40 AM

Hi Water bear.. i am testing with tablets (dpd1 phenol red and alkalinity) that you drop into a 3 compartment scale reader (don,t know the make)
The bromine llevel on the indicator stops at 11ppm but is a deeper pink than that so is a lot higher. Interestingly when i test with strips which i have also got the ph does read about 6.8 ph but with the tabs above 8.4ph (again where it stops on the scale) and is a very deep pink colour. which one is right. guessing the strips from your last info. I have not added any dry acid as i wanted to see what came back on here. Good job as i would have been making the water even more acidic.
So the ph is not high but low due to the acidic conditions of the water. So what do you suggest an empty and refil.?????

#6 jeffinpickering

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Posted 13 September 2012 - 08:48 AM

I would suggest you leave the cover off in the sun for a bit, until your bromine level drops to around 5-7ppm, then test your pH to see what it really is and take it from there.

Ways Bromine sanitizer levels will drop:
1. Using the tub
2. Sunlight
3. Something growing in the tub
It isn't going to just drop on it's own, so if you shocked it to 11+ppm, covered it, and left it for a week, and have an ozonator, it's not likely to move much, even if you left the floater out.

#7 waterbear

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Posted 13 September 2012 - 08:48 PM

chem geek, with bromine the phenol red will not convert into clorophenol red but rather a mixture of bromophenol red ( very pale yellow to red from pH 5.2 to 6.8) and this is converted either partially or fully to bromophenol blue (pale yellow to blue from pH 3.0 to 4.6) depending on bromine level with mostly bromphenol blue above 20 ppm bromine. (while chlororphenol red is yellow to red in the range of 4.8 to 6.4 in high chlorine situations) so in a bromine system with pH at 5.8 the actual color would depend on just how high the bromine is and the ratio of the mixed indicator created with the bromophenol red producing the red orange of phenol red at about pH 7.4 while the bromophenol blue contributes a blue color causing the final color to be in the red to red violet range while at lower pH of around 5.2 the color would either appear more yellow at lower bromine levels to a blue at higher bromine levels when there is more conversion with bromophenol blue proving once again that bromine chemistry is different and more complicated than chlorine chemistry! :blink:

jeffinpickering, I agree with your solution to the problem!

barnlsley_teaher, that means your strips have a halogen inhibitor built into the test and your tablets do not, making the strips a better test. Are your tablets from Palintest by any chance?
I've tested more water than I ever care to think about!
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