DPD or FAS-DPD

[AZAA]

The Taylor K-2006 provides two options for testing Cl. The Free, Combined & Total (DPD) method directly measures Total Cl from which you subtract Free Cl to achieve Combined Cl or TC-FC=CC.
The Free & Combined (FAS-DPT) method is more complicated and allows you to determine CC directly, then FC + CC = TC.
I don't think I need to perform both, but which is the most popular to use? Is there a consensus on this?

 

[PoolStored]

Use the FAS-DPD. More accurate. We only care about FC and CC.

Use a 10mL sample. Every drop is .5 FC.

You don't need to do CC every day. I do it maybe twice a year. If you maintain your FC for your CYA, you will likely never see a CC above .5. Link-->FC/CYA Levels

Basic Pool Care Schedule

This basic pool care schedule can guide you in creating your own pool care routine. Regular pool maintenance will keep your water sparkling!

www.troublefreepool.com

 

[Bperry]

The Taylor K-2006 provides two options for testing Cl. The Free, Combined & Total (DPD) method directly measures Total Cl from which you subtract Free Cl to achieve Combined Cl or TC-FC=CC.
The Free & Combined (FAS-DPT) method is more complicated and allows you to determine CC directly, then FC + CC = TC.
I don't think I need to perform both, but which is the most popular to use? Is there a consensus on this?

Note that TC is not a useful number. The two numbers needed to calculate TC are useful though.

 

[AUSpool]

Same, FAS/DPD and CC as needed. My most regular tests are the FC (FAS/DPD) and pH.
The 2000 comparator that comes with the K2006 can be used for CyA, DPD or FAS/DPD but the K2006 kit only includes the reagents for the FAS/DPD and CC tests.

Don’t know why it’s called the FAS/DPD test, it should be called a DPD/FAS test.

 

[Newdude]

Does this help answer it ?





Two scales, 0 to 5 for FC, and 0 to 10 for bromine, neither particularly accurate to give you an actual number.


If your CYA is still high, you need way more than 5 FC per day so the block test is no Bueno.

 

[AZAA]

Does this help answer it ?

View attachment 624314



Two scales, 0 to 5 for FC, and 0 to 10 for bromine, neither particularly accurate to give you an actual number.


If your CYA is still high, you need way more than 5 FC per day so the block test is no Bueno.

I just drained and refilled my pool so I'm easing the CYA in slowly to keep things under control. Thanks

 

[AZAA]

Use the FAS-DPD. More accurate. We only care about FC and CC.

Use a 10mL sample. Every drop is .5 FC.

You don't need to do CC every day. I do it maybe twice a year. If you maintain your FC for your CYA, you will likely never see a CC above .5. Link-->FC/CYA Levels

Basic Pool Care Schedule

This basic pool care schedule can guide you in creating your own pool care routine. Regular pool maintenance will keep your water sparkling!

www.troublefreepool.com

Thank you. Of course it's the more complicated method .

 

[AZAA]

Does this help answer it ?

View attachment 624314



Two scales, 0 to 5 for FC, and 0 to 10 for bromine, neither particularly accurate to give you an actual number.


If your CYA is still high, you need way more than 5 FC per day so the block test is no Bueno.

Same, FAS/DPD and CC as needed. My most regular tests are the FC (FAS/DPD) and pH.
The 2000 comparator that comes with the K2006 can be used for CyA, DPD or FAS/DPD but the K2006 kit only includes the reagents for the FAS/DPD and CC tests.

Don’t know why it’s called the FAS/DPD test, it should be called a DPD/FAS test.

Thank you for taking the time to answer.

 

[AZAA]

Use the FAS-DPD. More accurate. We only care about FC and CC.

Use a 10mL sample. Every drop is .5 FC.

You don't need to do CC every day. I do it maybe twice a year. If you maintain your FC for your CYA, you will likely never see a CC above .5. Link-->FC/CYA Levels

Basic Pool Care Schedule

This basic pool care schedule can guide you in creating your own pool care routine. Regular pool maintenance will keep your water sparkling!

www.troublefreepool.com

Thank you.

 

[AUSpool]

The Taylor K-2006 provides two options for testing Cl. The Free, Combined & Total (DPD) method directly measures Total Cl from which you subtract Free Cl to achieve Combined Cl or TC-FC=CC.
The Free & Combined (FAS-DPT) method is more complicated and allows you to determine CC directly, then FC + CC = TC.
I don't think I need to perform both, but which is the most popular to use? Is there a consensus on this?

It’s a bit complicated because both the comparator and instructions in the K-2006 are the same as used in the K-2005. It saves on production costs to make one comparator that can be used in multiple kits. The 9056 comparator found in the K-2006 & K-2005 can also be used to determine bromine via the DPD method. But, although the K-2006 comparator has the (Cl Br) option the K-2006 kit only has the FAS/DPD reagents and you follow the FAS/DPD instructions. When the r0003 is added to the used FAS/DPD mix we are now titrating for CC’s directly with the FAS reagent. Both FC and CC’s are direct measurements. If you really want to FC + CC = TC but there is no need to know the TC value.

The difference is in the K-2005, same comparator, same instructions but the K-2005 only has the DPD reagent that measures FC to 10ppm via colour matching and you disregard the FAS/DPD instructions, following the DPD instructions. This time when the r0003 is added to determine the CC’s it is actually measuring TC. So to get CC it’s TC - FC = CC. You can imagine though that at 0.5 to even maybe 2.0ppm CC the color variation would be very hard to detect, or dare I say, guess.


I believe @Newdude showed use the TFpro comparator with OTO/pH, this one is the Taylor 9056, CyA is on the other side.



And the instructions that include both DPD and FAS/DPD instructions. Note the ‘or’, one or the other.