Your test kit is an inexpensive (and not very good) 4 way test kit sold under the Hydro Tools brand name. The same kit is sold under different brand names (for example, it's the same as the Ace Hardware 4 way test kit). It does NOT measure up to 12ppm chlorine. The pH reagent is not a blended one and requires the addition of chlorine neutralizer, so pH readings can be suspect. The Acid Demand test is not very accurate at all and practically useless. The Total Alkainity test uses a very dilute bromothymol blue indicator (color change of pale blue to almost colorless yellow) so it is very difficult to see the endpoint of the titration (drop count)compared to the blended indicators used in better kits from Taylor and Lamotte that change from a deep and distinct green to red) If I am not mistaken the kit comes from China (as is most of the stuff imported by Swimline Corp, the parent company of Hydrotools) and , IMHO, is not worth the price of the plastic case it comes in.
I would STRONGLY suggest that you get a Taylor K-2006. There is NO comparision to the ease of use and precision of the Taylor kit compared to what you currently have!
I suspect I know how you are getting the reading of 12ppm . Many comparators have two scales, one for chlorine and one for bromine side by side. Bromine readingss are twice the chlorine reading. so the scale will say 1 on one side and 2 on the other and you are reading that as 12. The other possibility is that your comparator goes up to 6 ppm chlorine and 12 ppm bromine and you are reading the bromine scale.
I used to work with a CPO (Certified Pool Operator) that kept writing down a chlorine reading of 3.6 in the pool logs. I asked how he got that type of precision with the kit we were using (Taylor K-2005)when he tested our two commercial swimming pools where we worked. He showed me the 3 and the 6 on the comparator. I explained that the chlorine was 3 ppm, that the other set of numbers was for bromine, and then had a LONG talk with our boss!
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