DPD for daily testing?

geko29

Gold Supporter
Apr 27, 2018
137
Schaumburg, IL
I've been having a lot of trouble reading the pH comparator block on my K-1001, so I just picked up a Taylor 9056 and the requisite reagents. This indeed is MUCH easier to read. Since I have it, I've been playing around with the DPD test, and so far it seems fairly accurate. For example, this morning, I estimated FC at 4.0 based on the DPD test (looked like about midway between 3 and 5), and then got a result of 4.5 from the FAS-DPD test.

Given that, does it make sense to go ahead and use just the 9056 tests during the week, and only pull out the FAS-DPD on the weekend when I do the full battery of tests?
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,930
San Dimas, CA (LA County)
Lots of us get lazy about testing once we know our pool chemistry intimately. I often only use the OTO test (yellow) from my TF100. If it looks like the brightest color, I know I'm above minimum and can just dump in the usual.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,363
Tucson, AZ
That’s what I do.

By the way, you can use your R-0871 titrant to titrate the DPD to a clear endpoint. The volume of the 9056 on the FC side is 9.5mL so it’s very close to the 10mL sample size one would use with the DPD powder. So you can figure roughly 0.5ppm/drop.

Just note though that the 5 drops of R-0001/R-0002 will only cover about 10ppm FC. So you really don’t want to use that test for any high chlorine readings.
 

JJ_Tex

Bronze Supporter
Jul 17, 2019
1,723
Prosper, TX (DFW)
I assumed most people used the smaller FC and PH test daily, then the full battery of test weekly. Of course there are times when you would need to test something more often, but that works for me.
 

geko29

Gold Supporter
Apr 27, 2018
137
Schaumburg, IL
Thanks all!

That’s what I do.

By the way, you can use your R-0871 titrant to titrate the DPD to a clear endpoint. The volume of the 9056 on the FC side is 9.5mL so it’s very close to the 10mL sample size one would use with the DPD powder. So you can figure roughly 0.5ppm/drop.
This is excellent, I did not know that. Will check that out.

Just note though that the 5 drops of R-0001/R-0002 will only cover about 10ppm FC. So you really don’t want to use that test for any high chlorine readings.
Yeah I have a SWG now. :) So I'm really just trying to make sure I'm somewhere in the neighborhood of 5ppm, and not drifting up or down significantly where I'd have to adjust runtime or power. Not worried about the test bleaching out, and I would absolutely use the FAS-DPD if I had to SLAM for some reason.
 

Randrx2

Bronze Supporter
Dec 13, 2018
374
Orlando, FL
I have a hard time with the color comparator so I always use the FAS-DPD method. I also purchased the .25 lb tub of powder and the 16oz bottle of R-0871 reagent. I do not see me ever getting through powder, but the reagent bottle lasted me about a year. I check chlorine every day, sometimes twice a day. I also did a couple SLAMs. Having that much on hand takes the worry out of testing during a SLAM.