FAS-DPD question

[PoolAdmiral]

So basically my question is simple.
If I’m using the 10ml sample, do I use one or two scoops?

Reason I ask is because I read somewhere on this forum that it’s only 1 scoop. But the instructions on the k-2006c never mentions 1 scoop for the 10ml sample. Any thoughts?

 

[Texas Splash]

One scoop is fine for 10ml. The 2-scoop thing from the K-2006 is based on the 25 ml sample.

 

[Homebrewale]

One scoop is fine for 10ml. The 2-scoop thing from the K-2006 is based on the 25 ml sample.

Actually, it isn't. The instructions in the K-2006 are for both the 10 ml and 25 ml sample. In step 2 of their instructions, they don't say this step is for the 25 ml sample. It's actually for either sample size.
Instruction #5165 (for K-2000, K-2005, K-2005-SALT, K-2006, K-2006-SALT, K-2007, K-2009, K-2015)

 

[DaveTheAccountant]

This has confused me, too. The TF-100 instructions say one scoop.

 

[Donldson]

One scoop is plenty for the 10ml sample.

 

[Lake Placid]

Actually, it isn't. The instructions in the K-2006 are for both the 10 ml and 25 ml sample. In step 2 of their instructions, they don't say this step is for the 25 ml sample. It's actually for either sample size.
Instruction #5165 (for K-2000, K-2005, K-2005-SALT, K-2006, K-2006-SALT, K-2007, K-2009, K-2015)

It’s a general instruction assuming you’d use the 25ml sample size to ensure you have enough reagent. You’ll note it also says if the sample flashes keep adding R-0870 until it turns pink…..that could be 2 scoops or 500 scoops. Bottom line for a 10 ml sample 1 scoop should be enough and if it flashes add more scoops until it holds pink. If it doesn’t turn, you have no chlorine.

 

[DaveTheAccountant]

What are the consequences of adding two? Given the TFP methodology and following the instructions to the letter, have some been getting unreliable results?

 

[Lake Placid]

What are the consequences of adding two? Given the TFP methodology and following the instructions to the letter, have some been getting unreliable results?

Other than wasting reagent nothing. If the sample holds pink with 1 scoop that’s enough.

 

[mgtfp]

If it turns pink, it's enough powder. If it doesn't turn pink, try another scoop before concluding that FC is zero.

If still clear after two scoops, and still not turning pink after adding R-0003 for the CC-test, use the OTO test to confirm that there is indeed no chlorine. If OTO goes yellow, FC is either sky-high, bleaching out the DPD-powder. Or the powder has gone off.

 

[wireform]

If it turns pink, it's enough powder. If it doesn't turn pink, try another scoop before concluding that FC is zero.

I've always concluded no chlorine with one heaping spoon full and no pink color.

 

[mgtfp]

I've always concluded no chlorine with one heaping spoon full and no pink color.

Usually yes. But it could also mean that extremely high FC bleached out the DPD powder.

 

[Donldson]

following the instructions to the letter

These instructions?

 

[SteveK52]

These instructions?

View attachment 565097

I've been using 1 scoop for 5 years with no problem, why waste the reagent?

 

[DaveTheAccountant]

These instructions?

View attachment 565097

No, I am referring to the discrepancy in the Taylor instructions and those.

 

[Donldson]

No, I am referring to the discrepancy in the Taylor instructions and those.

What discrepancy? The k-2006 instructions are for a 25 ml sample with a precision of 0.2 ppm. The TF-100 instructions are for a 10 ml sample with a precision of 0.5 ppm.

That Taylor didn't have the space to offer an entirely different instruction set for use of a 10 ml sample does not change the basic math of the tests. If it takes 2.5x more water to do the 25 ml sample than the 10 ml sample and it takes 2.5x more R-0871 to perform the 25 ml sample than the 10 ml sample, then it does not stand to reason that it requires the same amount of R-0870 to run both tests.

 

[wireform]

So let me clarify, I use solely the TF-100 and one of the following scenarios are what I'm working with. Either it's opening a winterized pool so no chlorine means non lasted all winter as many time there's a trace left or it's a pool I'm on top of so over chlorination isn't ever something I ever had as usually it's where did the chlorine go kind of thing but a new customer in the middle of a season I may try the second scoop if it didn't turn pink but honestly it never happened yet.

 

[DaveTheAccountant]

What discrepancy? The k-2006 instructions are for a 25 ml sample with a precision of 0.2 ppm. The TF-100 instructions are for a 10 ml sample with a precision of 0.5 ppm.

That Taylor didn't have the space to offer an entirely different instruction set for use of a 10 ml sample does not change the basic math of the tests. If it takes 2.5x more water to do the 25 ml sample than the 10 ml sample and it takes 2.5x more R-0871 to perform the 25 ml sample than the 10 ml sample, then it does not stand to reason that it requires the same amount of R-0870 to run both tests.

Taylor does offer 10ml instructions and says to use two scoops.

 

[Texas Splash]

Taylor does offer 10ml instructions and says to use two scoops.

We may be splitting hairs with verbiage. Here at TFP we state in our instructions "Using the small spoon shaped end of the dipper, add one heaping dipper, or two level dippers, of R-0870". On the Taylor website testing reference materials they do lump/combine both sample size methods by mentioning 2 scoops (see below), but they don't clarify if those scoops are level.

Here at TFP our experts and scientists have determined that one heaping scoop provides the same reliable result and two level scoops. Our goal at TFP is not only ensure reliable/accurate testing, but to save pool owners money and reagents. Adding more than one "generous/heaping" scoop of powder to a 10 ml sample may simply be wasting precious reagent. Still, if you wish to add two level scoops that's up to you. Either way provides the same result.

FAS-DPD Chlorine Test

The FAS-DPD chlorine test is used to find the level of Free Chlorine in the … Read more…

www.troublefreepool.com

 

[dfwnoob]

Taylor also has a vested interest in selling more reagents. Maybe that's why they say to use 2 scoops, maybe it isn't. Maybe they're Raisin Bran enthusiasts.

I don't really care what Taylor says in this particular regard because evidence gathered here over many years of testing and my own empirical evidence from testing my own pool and never using two "dippers" worth of powder, suggests that it isn't necessary.

 

[duraleigh]

1. If the sample turns pink, you have added enough R-870 and the test will work

2. If it doesn't turn pink, you likely have no chlorine. You can try another scoop but it will probably remain clear

3. If the solution "flashes" pink and then very quickly turns back to clear you can be sure you have VERY high chlorine and will need another scoop of R-870 for it to remain pink and allow you to complete the test.

4. Once the sample goes from pink to clear, The test is over. Left alone for a few minutes there is a good chance the sample will return slightly pink but that is NOT part of the test and should be disregarded