Testing Free Chlorine

leslieann3583

Member
Mar 25, 2018
10
Fort Worth, TX
Hello,

Is there a substitute to the R-0870 dipper when testing for FC? I feel like I can't ever get the scoop level and would like to just use liquid instead for accuracy's sake... I went to Leslie's and they gave me a little package of R-0600 and R-0014 (sold together) with no directions, he told me to just replace the R-0870 with the R-0600 and the R-0871 with the R-0014 however, now that I'm reading online, it says that this is to test TC only. Any advice?
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
he told me to just replace the R-0870 with the R-0600 and the R-0871 with the R-0014 however, now that I'm reading online, it says that this is to test TC only. Any advice?
LA, it sounds as if Leslie's gave you something like THIS. The saleman is confused. The yellow capped R-0600 only tests for the presence of chlorine up to 5 FC. It is not designed to replace the R-0870 power or be used with the R-0871 drops. The powder & drops (FAS-DPD) go together, can test higher levels of FC, and are much more accurate. The red capped R-0014 only tests your pH. Hope that helps.
 
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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,049
Tucson, AZ
You can buy a DPD based colorimeter test kit like a Taylor K-1001 that uses the R-0001/R-0002 reagents BUT it has limitations as to the graduations in the FC scale and the maximum FC level allowed. I use it more as a daily spot test and save the accurate testing for the weekend.

As others have said, the amount of powder added is not critical as long as it is just a full scoop.
 
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Oly

Gold Supporter
Jun 28, 2017
698
Fresno, CA
Yes I like using the Taylor K-1001 to test Cl levels in my hot tub while I'm in the water.

Any idea why the color changes after several minutes of sitting? After the initial reading the color will lighten significantly changing the reading by several ppm. I always use the initial test results but am curious why the change over time.
 
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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,049
Tucson, AZ
Yes I like using the Taylor K-1001 to test Cl levels in my hot tub while I'm in the water.

Any idea why the color changes after several minutes of sitting? After the initial reading the color will lighten significantly changing the reading by several ppm. I always use the initial test results but am curious why the change over time.
Several factors - high CH levels causes precipitation due to the phosphate buffers used and that changes the color (you’ll see the precipitate clump at the bottom). Also, the dye (DPD) has two forms when it reacts with chlorine. The predominant form is the pink color you see when chlorine oxidizes the dye molecule. There’s also another reaction product that can form which is colorless but it forms at a much lower level relative to the pink product. However, given enough time, the clear product will form. In addition to all that, the oxidized pink form of the dye is not stable and so it will revert back to its reduced form (clear) over time.

So, as you mention, you take the reading right away and ignore any color changes after that.
 
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