TA test color change?

[savdoc2]

In the instructions for the TA test it states when the green color changes to "red". Up until recently I never saw a red color - but pink instead. I have been doing this test for 4 years now and only ever saw pink. Recently we got our hot tub going again and now I occasionally see red - but still sometimes pink.

Why would I see red sometimes and pink other times?

 

[chem geek]

Higher halogen (chlorine, bromine) levels would have the color go from blue to yellow instead of green to red. So at intermediate halogen levels this would be more of a blue-green to a pink assuming pink is a mixture of yellow-red (I think that's more of an orange). That's my best guess. What sort of FC level do you have when you do the TA test? You can see if adding more thiosulfate drops (R-0007) in the beginning changes the appearance.

 

[savdoc2]

In my pool, I always get a pink color regardless of the FC level. I have had FC levels anywhere from 3-25 this year and always got a pink color.

In my hot tub, I sometimes get pink and sometimes get red. FC levels have varied from 0 (new fill) to 12, but high or low doesn't seem to be a determining factor. The color always appears green after adding R-0008. I thought that water temp might be a factor, but I have ruled that out as well.

I can check on adding more or less drops of R-0007 and see if that changes anything.