robquick Posted August 7, 2017 Report Share Posted August 7, 2017 Hi, I normally run my tub on liquid Chlorine however, I ran out a few months back and have been using Dichlor. I've been a bit slack with checking TA and Ph so completed a full test last night and noticed that the Ph was very low (6.8). I slowly increased the Ph up to 7.5 however, the TA has shot up to 125...........when running running liquid Chlorine I normally have the TA at 40. The TA is normally very stable albeit it normally rises slowly as the PH rises but is easily reduced by reducing the PH. Where have I gone wrong ? Does liquid Chlorine behave differently to Dichlor ? Should I have air-rated the tub to increase PH rather than using chemicals which in turn have increased TA ? How do I correct it ? Use PH reducer to bring PH AND TA down and then air-rate to push PH back up ? Thanks. Quote Link to comment Share on other sites More sharing options...
MPurcell Posted August 8, 2017 Report Share Posted August 8, 2017 Dichlor is acidic, so it reduces pH and thus TA. Bleach / liquid chlorine is almost pH neutral. Additionally, dichlor contains cyanuric acid (CYA). For each 10 ppm of chlorine you add with dichlor, you add 9 ppm of CYA. It doesn't take long with dichlor to put the CYA way too high. The CYA in a chlorine hot tub should be around 30 ppm, no more than 40 ppm. In two months of using dichlor, you could easily be well over 100 ppm CYA. See the Chlorine / CYA Chart to see what it means. If you are not familiar with it, you should read the dichlor/bleach method in a nutshell sticky post above in this forum. Quote Link to comment Share on other sites More sharing options...
robquick Posted August 9, 2017 Author Report Share Posted August 9, 2017 Hi, Thanks for the reply. My TA was 125 so I used PH reducer to bring the TA and PH down. As it stands my TA is 90 and my PH is 6.8. I've tried aerating the water for about 2 hours now with every blower and jet on however, the PH has only moved to 7.0. Would you expect such a small rise in PH having aerated for 2 hours. Is it a case of persevering, or am I doing something wrong ? Thanks. Quote Link to comment Share on other sites More sharing options...
dlleno Posted September 15, 2017 Report Share Posted September 15, 2017 A TA of 90 is, by itself, perfectly fine, so what are you trying to achieve? there's nothing magic about the TA number itself if your water is balanced or a slightly negative saturation index -- higher TA values of course will encourage pH drift, but if you don't have that problem why are you trying to reduce TA? the more important goal is to maintain pH, and through experimentation you will find what TA values give you the best results. Quote Link to comment Share on other sites More sharing options...
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