Dpd test question
- Thread starter Shaun campbell
- Start date
The FAS/DPD powder test: Measuring chlorine VERY precisely, even up to 50ppm+
The liquid test is really a more of "yeap there is chlorine in the water" kind of test.
The liquid test is really a more of "yeap there is chlorine in the water" kind of test.
- May 23, 2015
- 24,403
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Yes and no @kimkats
The yellow OTO chlorine test is useless except as a “presence of chlorine” test.
The liquid DPD test (R-0001/R-0002 Taylor reagents) is accurate as an FC test but has limitations because it’s a color comparison test. So the color swatches have to have enough saturation difference in order for the human eye to register a color difference. This results in slightly wider ranges as you go up the scale.
The DPD-FAS test (the “powder” test) is the exact same chemistry as the liquid DPD test only one uses the FAS titrating reagent to force a color change (pink to clear) which is a lot easier for the eye to see. This results in better accuracy.
I use the liquid tester (DPD color comparator) all the time for daily spot testing of FC and it is dead-on accurate with the powder test. I use the DPD-FAS test only when I want to know the FC/CC accurately.
Pro tip - If you use the FAS titrating reagent (R-0861) with the liquid DPD test and you know how to do the math, you can get exactly the same results as the powder test
The yellow OTO chlorine test is useless except as a “presence of chlorine” test.
The liquid DPD test (R-0001/R-0002 Taylor reagents) is accurate as an FC test but has limitations because it’s a color comparison test. So the color swatches have to have enough saturation difference in order for the human eye to register a color difference. This results in slightly wider ranges as you go up the scale.
The DPD-FAS test (the “powder” test) is the exact same chemistry as the liquid DPD test only one uses the FAS titrating reagent to force a color change (pink to clear) which is a lot easier for the eye to see. This results in better accuracy.
I use the liquid tester (DPD color comparator) all the time for daily spot testing of FC and it is dead-on accurate with the powder test. I use the DPD-FAS test only when I want to know the FC/CC accurately.
Pro tip - If you use the FAS titrating reagent (R-0861) with the liquid DPD test and you know how to do the math, you can get exactly the same results as the powder test
THANKS! I had no idea there was a good liquid test!!
- May 23, 2015
- 24,403
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
A K-1004 test kit (DPD color comparison for FC, pH, acid demand, TA) is a decent test kit to own for doing quick daily checking and I would even recommend it for hot tub owners. If all one wanted was the liquid DPD test, then the K-1001 kit has that. The DPD color comparison is better in my opinion especially if one gets the #9056 high-range comparator block from Taylor (FC 1, 2 , 3, 5, 7.5, 10ppm and a pH comparator). The ranges are a little wide but the color contrast are easy enough to see so you know roughly where your pool is at. I use this all the time for my pool and reserve my R-0870 powder for more accurate Saturday morning testing.
Similar threads
