CL color test / wait time?

[JonoVegas]

Been using the color PH/CL test kit for years. Just happened to notice if I leave the sample sit a little while after putting in the drops my CL actually rises a bit. Is there a best practice to wait a couple of minutes after putting in the CL test drops before checking color for the CL reading?

Normally I am in a hurry and put the 5 drops in, measure and call it a day. Now I am starting to wait about 5 minutes after drops added before taking my reading and the CL measurement is alway higher by 1 or 2 if I wait the 5 minutes.

 

[mknauss]

The FAS-DPD FC test is complete once the sample turns clear. Record the drops at that time. Move on to the CC test, if desired, immediately.
The sample will turn pink again if you let it sit. Discard the sample once the testing is complete.

 

[Rancho Cost-a-Lotta]

It sounds like you may be describing the OTO test. The FC reading should be taking immediately. If allowed to sit, the color will change to reflect the total chlorine level, from which you can determine the CC. The test is not real accurate, so when it doubt, use the FAS/DPD test (powder/drops).

From Pool School:

This test measures TC, but if you watch closely it is possible to get a sense of the presence of CC. When you first add the drops of R-0600, the sample will immediately show the FC level. Then, over the next minute or so, it will drift up to the TC level. If you see the color changing, CC is present. Using the test in this way requires careful attention and a good ability to distinguish shades of yellow quickly.

 

[mknauss]

Good catch Mike. I do not ever use the OTO thing. Wish we could just eliminate it from the kit!!

 

[JonoVegas]

Thanks guys!