Testing CC with K-2006

[bottomcat]

I just bought my first real test kit (K-2006) and tried to test Free and Combined Cl. I used the 25 ml sample size. Free Cl measures 1.0 ppm (5 drops R0871). When I tried to measure CC, I added 5 drops of R0003 and the sample turned a very light shade of pink. I then added two drops of R0871 and it turned clear (I thought) but a minute later it looked pinkish so I added two more drops. I turned clear again, but a minute later was light pink again. This went on until I had added a total of 7 drops and I finally quit.

Am I doing something wrong? Does the sample bottle need to be closed to keep it from turning pink?

Thanks in advance!

[Kidney]

I just bought my first real test kit (K-2006) and tried to test Free and Combined Cl. I used the 25 ml sample size. Free Cl measures 1.0 ppm (5 drops R0871). When I tried to measure CC, I added 5 drops of R0003 and the sample turned a very light shade of pink. I then added two drops of R0871 and it turned clear (I thought) but a minute later it looked pinkish so I added two more drops. I turned clear again, but a minute later was light pink again. This went on until I had added a total of 7 drops and I finally quit.

Am I doing something wrong? Does the sample bottle need to be closed to keep it from turning pink?

Thanks in advance!

Not an expert here at all but re CC, I had the same experience with the liquid turning pinkish again when I waited some time. I don't think you need to worry about this. I believe the first time it turns clear when looking at the comparator tube from the side where you see the units (not from the top as it does look a different shade sometimes) is the one that matters. Let's see if the experts agree ;-)

[bottomcat]

Thanks Kidney. I'd love to hear if anyone else has observed this issue and whether or not I should be worried about my CC level. I will try using the 10ml sample and looking through the side of the tube as you suggest.

[Watermom]

You need to read the CC reading without letting it sit, so yours is fine.

Just use the 10mL sample instead of the 25mL. It will make your testing reagents last longer. You'll multiply the number of drops by 0.5 instead of 0.2.

[bottomcat]

Excellent. Thanks Watermom. Looks like I wasted 5 drops!

[Kidney]

Looks like Watermom agrees with my interpretation yeah!!! (And I recall reading that with the OTO test kit, one can guesstimate the CC level in the first three minutes of a TC test i.e. (?) if the solution turns dark yellow before becoming lighter there is some CC, not sure that can be used to infer how much though.)

So to get rid of CC, do we chlorinate the pool to 10 times FC level? Or is there another method?

[Watermom]

If you have a CC reading over 0.5ppm, you need to shock the pool. How high depends on your CYA level. More about the CYA/Chlorine relationship can be found here:> http://pool9.net/cl-cya/

[Kidney]

If you have a CC reading over 0.5ppm, you need to shock the pool.

Thanks Watermom, good rule of thumb! So no need to shock if below that: the weekly shocking recommendation I see here and there is really just a recommendation, not a requirement for sanitation then, correct?

[Watermom]

Thanks Watermom, good rule of thumb! So no need to shock if below that: the weekly shocking recommendation I see here and there is really just a recommendation, not a requirement for sanitation then, correct?

Correct. Who suggests weekly shocking? Pool stores and pool chemical companies who both stand to make money from people shocking their pools.