Yellow vs Pink C Tests?

Gebo

Bronze Supporter
Aug 23, 2023
231
VA
Two of my test kits use "yellow" as the color when trying to determine chlorine ppm and another uses "pink" as the reference color. I see they take different

reagents but what exactly am I checking. Is one better than the other? Why would I use one over the other?
 

The differences:

Taylor K-2005 / Leslie's 81330​

The Taylor K-2005 is a test kit that gets pushed by many larger “pool stores”. It tests pH, TA, CH, CYA VERY well, but it’s shortfall is how it tests chlorine levels. The K-2005 uses a “DPD” chlorine test which has three very large pitfalls:

1. The DPD chlorine test will NOT show accurate results above 5 ppm. This is an issue if you wish to follow TFP methods, as we teach that it’s best to maintain a ratio of chlorine to CYA, see the Chlorine/CYA Chart, not just a firm 1-4 ppm.

2. The DPD chlorine test uses “color-matching.” You add a few drops of reagent to the water and then match the pink sample color to the comparator. It’s easy to mismatch the true levels.

3. Perhaps worst of all, the DPD chlorine test's pink sample color can "bleach out." If the chlorine is well above the 5 ppm limit, the pink sample color after the reagent is added can fade out or even remain clear. This can lead one to believe the chlorine level is MUCH lower than reality, potentially leading to adding even more chlorine to the pool.

FAS/DPD chlorine test: (in tf100/pro & k2006)
This allows a user to test chlorine well above 5 ppm, up to 50 ppm, and is performed by counting drops to change the sample color from pink to clear, instead of trying to color-match to a comparator, making it very accurate to get your true FC and CC levels.

OTO (yellow drops) :
Only measures Total Chlorine up to 5ppm not Fc & cc separately.
The least accurate of the reagent tests.
Depends upon user color matching.
So simply an indicator if chlorine of any kind is present or not.

 
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