toby Posted August 27, 2012 Report Share Posted August 27, 2012 I like a high TA because the Ph appears to be relatively stable. I havent had to re-adjust the Ph over the last two years. I was wondering what unwanted side effects I might be instore for? Also is there a maximum recommended level for TA? I set my TA at 150 on refill. I am using a 3 part bromine system. Sodium Bromide Bank of 30ppm, Sodium Bicarbonate TA 150, Calcium Hypochlorite Shock and BCDMH Bromite Tablets. I generally run the Spa at a 3ppm level as my willing elves can easily read that on the comparator! Re Stable Ph: The Ph zooms during shocking, but returns once the shock level returns to normal. Quote Link to comment Share on other sites More sharing options...
Spanky Posted August 27, 2012 Report Share Posted August 27, 2012 150 does seem high but if your pH is stable then don't worry about it. It's more common to see spas stabilize at TA of 60-80 but clearly every situation is different Quote Link to comment Share on other sites More sharing options...
waterbear Posted August 27, 2012 Report Share Posted August 27, 2012 The pH is not going up on shocking, That is a chemical interference from the high santizer level that is producing a false high pH reading. How are you testing (type and brand of test kit?) Quote Link to comment Share on other sites More sharing options...
toby Posted August 27, 2012 Author Report Share Posted August 27, 2012 Thanks, A couple of years ago I'd been chasing the Ph and always wondered why it appeared unstable. I'm using a Lovibond 'DPD No. 1' which I has assumed was compatible with comparators. Sell by date being 2018. Out of interest what are the differences between DPD 1 and 3? Quote Link to comment Share on other sites More sharing options...
waterbear Posted August 28, 2012 Report Share Posted August 28, 2012 DPD 1 tests free chlorine, DPD 3 contains and iodide salt and will test total chlorine. We actually recommend FAS-DPD testing over DPD testing and if the pH reagent does not contain a chlorine neutralizer it can read high falsely when the chlorine is only as high as 3 ppm.I see by your IP address that you are in the UK so the only FAS-DPD test kit you really have access to is LaMotte 7022. Quote Link to comment Share on other sites More sharing options...
toby Posted August 28, 2012 Author Report Share Posted August 28, 2012 Hi Waterbear, My limited understanding of using a three part bromine system was that the Calcium Hypochlorite acted as an oxidiser to convert part of the Sodium Bromide bank to HoBr. I thought any chlorine produced would be rapidly used or evaporate. If DPD-1 is measuring chlorine, I am confused about what it is reporting on when I am not shocking the spa? Quote Link to comment Share on other sites More sharing options...
waterbear Posted August 29, 2012 Report Share Posted August 29, 2012 With bromine DPD 1 will measure your bromine sanitizer level. Quote Link to comment Share on other sites More sharing options...
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