FYI: 2019 Pre-closing Jack's #2 Treatment >> 2020 Opening Strangeness

calinb

Well-known member
Jul 18, 2018
116
N. Central, ID
This is the third time I've opened this pool, which we acquired with our new home just over two years ago. I closed the pool last December, which is a very late closing here in Idaho, because I wanted to give my late-season Jack's Magic #2 treatment the longest time possible to work on copper stains that I believe were the result of the previous owner using trichlor with copper.

As expected, the sulfamic acid in the #2 treatment resulted in nearly all the chlorine reporting as CC. Even after 12 weeks (most of it above the recommended 60 degree water temperature), my pool still read nearly all CC (last December). Now I read about 2 ppm FC and 14 ppm CC (I'm SLAMing). In reality, the FAS DPD test doesn't work well at all, because the CC bound from the sulfamic acid takes a fair amount of time to react. The same is true of OTO. Jack's recommends just using OTO and I think OTO works just as well as FAS DPD, due to the unknowns about sulfamic binding of chlorine and the uncertainties of any test in a sulfamic acid treatment chemistry.

The first two seasons that I opened the pool revealed CYA (and, naturally, TC) to have fallen to zero but the water was clear. Not so this year. The CYA reading was nearly where it was when I closed (still a bit over 30 ppm) and the pool was green. This is day three of the SLAM. As best I could tell using both FAS DPD and OTO (diluted pool water 1:3 with fresh water) the pool did not discernibly consume chlorine last night. The water is clearing and the cloud is mostly white.

I know TFP experts advise not to use OTO with a diluted sample to establish and check SLAM chlorine levels, but there's really no point in doing FAS DPD because the clear to pink reaction time is so prolonged (not the normal re-occurance of pink due to a prolonged test time) OTO is cheap and easy but it takes about an hour to fully detect the sulfamic bound chlorine. In fact, there's no color at all for several minutes. I just set the comparator aside for an hour and then take the reading.

It was the same during the Jack's treatment and there's little technically known about how chlorine functions under the stain treatment or even what chlorine concentrations are needed during a SLAM. The bottom line is my pool is clearing normally.

During the #2 treatment, I noticed that chlorine demand was a bit higher than normal too--especially given the colder months. I don't know if it was because the chlorine was becoming bound in a sulfamic acid reaction or perhaps it was due to an "infection" in the pool.

Before I closed the pool, I used baking soda to balance the pool, as recommended by Jacks but I did not SLAM, faring stain precipitation. I didn't SLAM the the previous closing either but rather used Polyquat 60.

So the bottom line is a pool may behave a bit differently after Jacks's #2. From reports and my experience, it takes many months to "get it back" and probably a lot of chlorine too! In the meantime, the diagnostic aid of a FAS DPD FC vs. CC is obliterated--you'll just have to live with a somewhat uncertain TC/CC reading and the chlorine tests don't behave as usual.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,279
Tucson, AZ
I know TFP experts advise not to use OTO with a diluted sample to establish and check SLAM chlorine levels, but there's really no point in doing FAS DPD because the clear to pink reaction time is so prolonged (not the normal re-occurance of pink due to a prolonged test time) OTO is cheap and easy but it takes about an hour to fully detect the sulfamic bound chlorine. In fact, there's no color at all for several minutes. I just set the comparator aside for an hour and then take the reading.
Your understanding here is not correct. Leaving the sample to sit for minutes or hours is not how the DPD indicator works. What you are seeing is oxidation of DPD indicator by air and dissolved O2 in the water. DPD added to water with no chlorine will start to turn pink after a few minutes because the chemical is simply oxidizing over time. This is why the DPD method of chlorine detection needs to be carefully done or else there are a lot of positive color interferences that can happen.

You are correct that sulfamic acid reacts with chlorine and will cause the DPD-FAS test to show higher chloramines, but the reaction is fast and does not require time for the color to develop.

To correctly do the testing with DPD-FAS and your pool water being fouled with sulfamate is to do a total oxidizer (TO) test. Simply add the DPD power to the water sample and then 5 drops of the DPD Reagent #3. This will force all of the FC and CC's to convert the potassium iodide into triiodide anion (I3-) which will then react with the DPD and force it into it's pink state. Then you can titrate with the R-0871. You should do the full test in under one minute (use a SpeedStir) and then your result is Total Chlorine (TC). The number you get from that test will be far more accurate than trying to use OTO on a diluted water sample.

Over time, chlorine will eventually oxidize all of the sulfamate to sulfates and nitrates, but it takes a long time. Even when pool water is at full summer temperatures, it can take well over a month for the sulfamate interference to resolve. This why you typically want to drain the pool after using Jack's Magic #2 copper remover and send all of the copper out with the waste water. You then fill with fresh water and then balance.
 

calinb

Well-known member
Jul 18, 2018
116
N. Central, ID
Your understanding here is not correct.
I almost didn't post this FYI here and was expecting your reply JoyfulNoise, but perhaps others will benefit from my hands-on experiences--even if it only sets their expectations under similar circumstances. Have you ever done a prolonged, high concentration sulfamic acid treatment yourself (not that everyone's experiences are all the same, nonetheless)?

If I may make an equally blunt assessment of your knoweledge without getting banned here, I think your practical understanding is not correct. Like Richard Feynman said, when the results don't match the theory, your theory is wrong!

Leaving the sample to sit for minutes or hours is not how the DPD indicator works.
If it is not left to sit, the reading does not even come close to agreeing with an OTO test, and OTO is what Jack's recommends using during and after #2 treatments. If I do a FAS DPD test quickly, it reads about TC=4 (FC-2 CC-2) whereas OTO reads 16. The CC result from the FAS DPD test of sulfamic acid treated pool water is entirely dependent on timing--even when conducted inside of one minute, the result changes with timing. I don't see how your advice to use the FAS DPD can produce improved accuracy over an OTO test, given the extreme variablility of FAS DPD with timing when testing a sulfamic acid treated pool (or at least MY sulfamic acid-treated pool). Using CYA of 40 (my CYA is between 30 and 40), I need to SLAM at FC = 16. The pool is clearing very quickly and the amount of bleach I distributed into the pool and measured after a brief circulation time using both tests correlate to a TC reading of 16 ppm and not 4 ppm (I added an amount of bleach that I expected to produce 16 ppm and sure enough, the OTO (diluted sample) test reported 16 ppm and so did FAS DPD, but only if I delay the post-#3 reagent titration a bit). Because FAS DPD is so dependent on timing for post-sulfamic testing, I prefer the Jack's recommendation to use OTO, even though I must dilute the sample for a SLAM. Even if I assume 15 ml sample of fresh water and 5 ml sample each have 1 ml of measurement error (and I think I can read a small beaker better than that!), the error in a diluted OTO sample is still quite acceptable for the purposes of a SLAM and I actually think it's a better bet than the timing-dependent FAS DPD method.

Over time, chlorine will eventually oxidize all of the sulfamate to sulfates and nitrates, but it takes a long time. Even when pool water is at full summer temperatures, it can take well over a month for the sulfamate interference to resolve.
This is consistent with what I've experienced and I fully agree.

This why you typically want to drain the pool after using Jack's Magic #2 copper remover and send all of the copper out with the waste water. You then fill with fresh water and then balance.
Draining is not an option (It takes 19 water truck trips up a very unpaved, twisty and narrow grade to fill the pool.) After two years of replenishing with 4.4 ppm Fe spring water I'm using a CuLator Fillfast filter along with a CuLator egg and small monthly "maintenance" doses of sequestrant to catch trace metals until the CuLator egg can remove them. The first year, I just used the CuLator egg and sequestant (a large amount of Metal Magic treatment to remove iron stains) and the egg became very puffy and red brown after the stains vanished. I've had no trouble with iron stains coming back. Last year's egg didn't pick up any noticeable red/brown, but rather turned blue during the #2 treatment as I focused on removing the copper stains. I started using the Fillfast filter last year too. I know not everyone has had a good experience with CuLator and I think you've essentially condemned it as a fraud, but CuLator products function exactly as advertised for me (the egg does require the use of a sequestrant until the metal ions can be captured by the egg--a process of months rather than days).

BTW, I tested the copper stains with the Jack's test kit, Metal Magic sponge test, oxalic acid, citric acid, ascorbic acid, and sulfamic acid and only the Jack's #2 and the sulfamic acid were at all effective on the stains (which remained after my first Metal Magic battle against the Fe stains). This result, along with the blue color of the CuLator egg and a professional test of our spring water that only found Fe in any substantial concentration, has led me to conclude the last of the stains were copper from the copper-laced trichlor pucks the previous owner used.
 
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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
17,279
Tucson, AZ
It doesn't matter how beautiful your theory is, it doesn't matter how smart you are. If it doesn't agree with experiment, it's wrong. - Richard Feynman

As much as I loved the lectures of the good doctor, the logic of his quote above is fatally flawed. It assumes that the experiment is done correctly and that the experiment can proceed without error. It is only when our experiments are informed by the underlying rules of science that we can hope to perform them in a way that produces a meaningful result. You can perform the same bad experiment one time, or a thousand times, and the answer will still be the same, ie, garbage in = garbage out. And even when a "result" is obtained, one must always go back and test that result against the rules of science that we know to be true in order to arrive at the correct interpretation. The scientific method always starts with a hypothesis that is informed by the basic laws of science and then experiment is used to test the hypothesis; experiments without a hypothesis are meaningless. I prefer Einstein myself -

A theory can be proven by experiment; but no path leads from experiment to the birth of a theory. - Albert Einstein

Now I would point you to the chemistry of how DPD works. It is a phenylenediamine dye with two nitrogen units that can take one of two reaction pathways - the diamine is ionized into a zwitterionic form (a so-called Würster Dye that is pink colored) or into a colorless imide form. Both products are formed and their relative concentrations depend a lot on pH, the ratio of oxidizer to dye concentrations, the presence of interfering metal species, etc., etc.. When one leaves a sample of DPD dye and various chemical reactants to develop, there is no way to determine what is causing the color to form. So, over long reaction times, the DPD dye is worthless.

Sulfamic acid reacts with hypochlorite to form monochlorosulfamate. Monochlorosulfamate will react further with excess hypochlorite and form dichlorosulfamate. The primary reaction forming monochlorosulfamate is mostly irreversible while the second reaction of monochlorosulfamate and excess hypochlorite forming dichlorosulfamate is reversible but slow. Both chlorosulfamates are species that interfere with the CC side of DPD test. Neither of these compounds are strong oxidizers or strong sanitizer and so their presence in your pool is rather useless.

This is why I suggested you do the total oxidizer test - add R-0003 immediately to the sample with the R-0870 and then titrate. By doing so, you are getting roughly 4ppm TC....and that is the important value for your SLAM. The chlorosulfamates simple don't matter, they are going to be too slow as sanitizers to be of use. Over time they will breakdown slowly into chlorine/chloride, nitrates/nitrogen and sulfates. None of those reactions help you with your SLAM.

OTO is orthotolidine and it is sensitive to total chlorine levels and other oxidative species so given your mixed bag of chemicals, just like DPD, you are seeing the effects of all oxidation reactions on it. It is also well know to not be an accurate way of measuring chlorine as the color changes are not linear and repeatable - different water conditions and pH can yield slightly different shades of yellow & orange. I have had pool water with 2ppm FC and no CC’s show up as > 5ppm TC (bright orange) on an OTO test. Even the pool industry doesn’t consider it more than just a “presence of chlorine” test.

With all that said, it’s your pool and your money and you can see fit to do whatever you like with it. If you feel you are getting satisfactory results using diluted OTO testing, great. However, TFP will always recommend draining a pool after sulfamic acid treatment for copper stains as that is the most reliable method of ensuring no further issues. Using sequestrants and pouches of ion exchange resin (CuLators) are only masking the problem...and draining the pool owners wallet.
 

calinb

Well-known member
Jul 18, 2018
116
N. Central, ID
As much as I loved the lectures of the good doctor, the logic of his quote above is fatally flawed. It assumes that the experiment is done correctly
It's not flawed. Of course it assumes (requires) that the experiment is done correctly.. No great quote could possibly contain all the relevant caveats, which are covered in the Feynman quote by the many implications of the word "experiment."

Thanks for supplying the quote, verbatim!

and that the experiment can proceed without error.
Experiment without error is impossible. Every experiment contains error and it's accommodated by error analysis.

> A theory can be proven by experiment; but no path leads from experiment to the birth of a theory. - Albert Einstein

Einstein was clearly wrong here. In fact, the "birth of a theory" doesn't even require experiment. It may simply be guessed!

"Now I'm going to discuss how we would look for a new law. In general we look for a new law by the following process: First, we guess it." --Richard P. Feynman http://www.richardfeynman.com/Feynman on Scientific Method..mp4

Any idiot might possibly guess a hypothesis that proves to be true (which is often more difficult to do than making the guesses).

Of course Einstein was wrong about quantum mechanics and he never accepted it. ("God doesn't play dice with the universe" and all), whereas the advancement of quantum mechanics is where Nobel Prize-winning physicist Feynman excelled. Given that Feynman followed Einstein by a generation, the differences are not surprising.

My quantum mechanics Professor worked on the Manhatten project with Feynman. My Prof is the only person that I've ever met who I believe understood quantum mechanics but, then again, Feynman also said "If you think you understand quantum mechanics, you don't understand quantum mechanics." Finally again, I don't recall my Prof. ever claiming to understand it! ;)

With all that said, it’s your pool and your money and you can see fit to do whatever you like with it.
The previous owner used gallons of sequestrant for years without draining the pool and he still had stains. In two treatments over two years, I've eliminated most of the stains and use very little sequestrant (some is always needed, even with the eggs and Fillfast). Given that I've kicked the sequestrant habit and the iron stains have not returned after two years (I'll report on the copper stains after at least a full year when I'll hopefully have more confidence that Jack's #2 plus the CuLator program are a permanent fix), it is working for me indeed. I'm saving a lot of money on an ever-increasing sequestrant habit or expensive water tanker deliveries.
 
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