Alkalinity Problems in spa

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.

Alkalinity Problems in spa

Postby Di » Mon 26 May, 2008 13:40

When testing my spa water for total alkalinity with my Taylor test kit, the sample turns blue, rather than green. If you then add the drops to make the sample turn red, it turns yellow instead. What's up with that? The PH is a little low, 7.0 or so, and the testing drops are fresh and work fine on my pool tests. I use bromine in the spa, and it is reading high. The spa has not gotten much use this winter.

chem geek
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Postby chem geek » Mon 26 May, 2008 16:25

The Total Alkalinity (TA) test will turn from blue to yellow instead of green to red when the sanitizer level (chlorine or bromine) is very high. So that's what is happening in your case. The reading is still valid, but the colors are different as you have noted. You can read about this interference here. Note that the pH test will not be valid when the sanitizer level is so high though usually it will misread as being too high, not too low, so your pH may indeed be on the low side.

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