metronome Posted May 31, 2014 Report Share Posted May 31, 2014 New 450 gl. hot tub w/ corona discharge ozonator Knew we had soft water as you can't wash off soap. The first fill I completely over-dosed with bromine. I added 2 oz. bromide. Then foolishly filled a floater to the brim with tablets. This went on for 48 hours. Upon further research I read that I really didn't need a floater all the time, just activator. We did get a 2nd filter and rinsed and swapped them for 3 days per the installers advice. TA was 800, calcium hardness was 0 and the sanitizer was rendering the pH purple. I tried draining 50% of the water but still could not obtain a pH value with my Taylor kit even with adding thiosulfate. The pool supply store also said my bromine was 10ppm, phosphates 1000 and calcium hardness 70. I drained the tub, rinsed a filter and re-filled using an eco-one hose end filter. I've added NO bromide. Have been adding dry acid. TA is down to 100 but pH is still giving a purple response. Did a dilute bromine test at the 1.8 ml mark and obtained ~10ppm. Where is this halogen coming from?? Can the filters trap excess bromine when I OD'd it on the first fill. I'm stuck..... Quote Link to comment Share on other sites More sharing options...
chem geek Posted June 1, 2014 Report Share Posted June 1, 2014 I doubt your TA was 800 earlier. If you don't have your own proper test kit, which for Bromine is the Taylor K-2106, then you are really shooting in the dark. You don't drain out all the water when you refill, but you do get rid of most of it so you shouldn't be measuring that high a bromine level. Note that if you added activator (which is chlorine such as Dichlor) then even with no bromide bank your test kit will show bromine since it can't distinguish between chlorine and bromine. So if you added activator, then you've got chlorine. Quote Link to comment Share on other sites More sharing options...
metronome Posted June 2, 2014 Author Report Share Posted June 2, 2014 That is the test kit I have. Since I completely drained this last time and added no Bromide or activator, I'm wondering why I can't get a valid pH value and why would I get the the 10ppm running a dilute 1.8ml Bromine test?? This is still basically tap water as I've only added dry acid to lower TA. Could my municipal water supply have such a high level of chlorine that it will skew a pH test?? Quote Link to comment Share on other sites More sharing options...
chem geek Posted June 2, 2014 Report Share Posted June 2, 2014 Tap water can have up to 4 ppm FC which would look like up to 9 ppm bromine. That shouldn't be so high as to invalidate the pH test. The very high TA will tend to push up the pH though as you've gotten your TA down the pH should have been able to come down at least some as well. You can always add some thiosulfate drops (R-0007) to your sample before adding the pH indicator. The thiosulfate can influence the pH, but at least it should get rid of chlorine/bromine interference if that is what is happening so you can at least see if it changes. Quote Link to comment Share on other sites More sharing options...
metronome Posted June 2, 2014 Author Report Share Posted June 2, 2014 Tried the thiosulfate, one drop then two, still purple. I even had Taylor check the lot numbers and the reagents are fresh. I've never seen anything like this. Quote Link to comment Share on other sites More sharing options...
chem geek Posted June 3, 2014 Report Share Posted June 3, 2014 Do the R-0005 acid demand drops added to the sample with the pH indicator show any change? It should tell you how much acid is needed to lower the pH, but this does seem very strange though your TA reading was quite high. Quote Link to comment Share on other sites More sharing options...
metronome Posted June 3, 2014 Author Report Share Posted June 3, 2014 Funny you should ask W 0f W... as I was repeatedly being told that the purple was due to excess sanitizer I NEVER did an acid demand test untill 30 minutes ago. I kept adding dry acid and got TA down to 110 as of this afternoon. Well the acid demand indicated a 7.4 with the addition of TWO drops. Perhaps I've been dealing with tap water that is > 8.0 all along. One question... does excess bromine (if present) invalidate an acid demand test with purple water from a skewed pH test?? Quote Link to comment Share on other sites More sharing options...
chem geek Posted June 4, 2014 Report Share Posted June 4, 2014 Excess chlorine (> 10 ppm) or bromine (> 20 ppm) can invalidate the pH test and yes that is still invalid even using the acid demand drops. It does seem, however, that your tap water simply has pH > 8. The acid demand test, by the way, is nothing more than acid itself. Quote Link to comment Share on other sites More sharing options...
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