Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 6 of 6

Thread: DuPont Oxone (Monopersulfate) ? For Chem Geek.

  1. Back To Top    #1

    Join Date
    Jun 2011
    Location
    Cape Girardeau, Mo
    Posts
    125

    DuPont Oxone (Monopersulfate) ? For Chem Geek.

    From my understanding DuPont Oxone can interfere with combined chlorine testing as a false positive result and i am aware that Taylor even makes a reagent to counteract the effect that monopersulfate has on the test.

    So if monopersulfate were used in a pool how long before it dissipates to the point it no longer interferes with testing or does it even dissipate at all and the level just builds up like cya does?
    Steve Frakes
    15' X 48'' Intex Metal Frame
    Intex Sand Filter 16'' 2650 GPH
    Taylor K-2006 Test Kit
    BBB and Borated

  2. Back To Top    #2

    In the Industry

    Join Date
    Jul 2009
    Location
    London and France
    Posts
    574

    Re: DuPont Oxone (Monopersulfate) ?

    MPS doesn't build up in the pool so no worries there. How long depends on how much was used and how much work it has to do, much like chlorine. I used to add 2.2lbs and that lasted around 10-14 days.

  3. Back To Top    #3

    Re: DuPont Oxone (Monopersulfate) ? For Chem Geek.

    Yes, MPS does buildup in pools. Think of it this way. If you always maintain a good FC level and then add MPS say once or twice a week, there is nothing for the MPS to do. So it builds up. At about 45-50 ppm of MPS it get irritating to skin. DuPont even warns against this in their literature. They say it is a skin sensitizer. Once exposed and irritation developes, it takes less concentration the next time to cause irritation.There are many cases of MPS irritation in commercial pools where they add MPS by the calendar rather than when combined chlorine or organics buidl up. The same thing happens with dipersulfate, the other non-chlorine shock. In addition, the sulfate in these products can build up and become food for algae. Think fertilizer 6-6-6 is Nitrogen, Phosphate and Sulfate.

  4. Back To Top    #4

    Join Date
    Mar 2007
    Location
    San Rafael, CA USA
    Posts
    12,082

    Re: DuPont Oxone (Monopersulfate) ? For Chem Geek.

    MPS shows up as Combined Chlorine in the DPD test but as Free Chlorine in the FAS-DPD test. While MPS does not react with DPD dye directly, it acts as an oxidizer to the potassium iodide in the R-0003 reagent for the CC test when using DPD and it reacts with the R-0871 FAS-DPD reagent when using the FAS-DPD test. Either way, the interference can be removed by the Taylor K-2042 kit.

    As for how long MPS lasts, it depends on what there is to oxidize, but it is also affected by sunlight though not nearly as much as chlorine. It is not true that so long as there is chlorine present that the MPS will not oxidize anything. They are each selective oxidizers. For example, chlorine very quickly reacts with ammonia to form monochloramine (and more slowly oxidizes this eventually to nitrogen gas and some nitrate) while MPS does not react quickly with ammonia (or ammonium ion) as described in this paper. On the other hand, chlorine reacts rather slowly with certain organics while MPS reacts more quickly and in more varied ways. For example, chlorine forms combined chlorine through substitution reactions at nitrogen sites while MPS reacts with carbon-carbon double bonds to form epoxides. 2.2 pounds of (the triple salt of) MPS in 12,000 gallons is equivalent in oxidizing power to 4.4 ppm FC. Lasting around 10-14 days implies a loss of around 20-25% per day to end up with 0.08 (25% daily loss over 14 days) to 0.47 ppm (20% daily loss over 10 days).

    It is primarily the sodium persulfate contaminant that is irritating though this tends to react and therefore dissipate in a day or two. Yes, very high MPS levels themselves can be irritating, but as noted by Pb2Au that happens when not responsibly using MPS -- it is not a substitute for chlorine except when used with Nature2 in spas (as noted in this post, the silver ion of Nature2 reacts with the sodium persulfate so normally prevents it from being irritating).

    As for sulfate being food for algae, this is not a concern because it is not usually a limiting nutrient in pools. There is far more carbon, hydrogen, oxygen and nitrogen required compared to phosphorous and sulfur. Sulfur is primarily found in a couple of amino acids and therefore proteins/enzymes containing such amino acids (as opposed to phosphorous used in the phosphate backbone of DNA, RNA and in the ATP energy carrier and in phospholipids in cell membranes). Nevertheless, actual sulfur content in algae is roughly similar to that of phosphate so though a macronutrient, far less is needed than carbon, hydrogen, oxygen and nitrogen. There are many pools that have never used MPS or dry acid products and have very low sulfate levels in fill water that readily get algae if there is too little sanitizer and there are sufficient phosphates (and possibly nitrates). Also, most fill water has more than enough sulfates to supply sulfur to algae and bacteria. Remember that for phosphates to be limiting enough to prevent algae growth, the level needs to be below around 100 ppb which is 0.1 ppm while the typical sulfate level in fill water in the U.S. has a median of 4.6 ppm (mg/L) and is even 0.5 ppm or higher in rain (see Figure 6 in this link). There are concerns with high sulfate levels (above 300 ppm) with regard to plaster as noted in this thread.

    The three numbers for fertilizer are for nitrogen, phosphorous, and potassium (N-P-K). It is only when there is a fourth number where that represents the sulfur content (N-P-K-S).
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

  5. Back To Top    #5

    In the Industry

    Join Date
    Jul 2009
    Location
    London and France
    Posts
    574

    Re: DuPont Oxone (Monopersulfate) ? For Chem Geek.

    Thanks Richard, very interesting, especially my usage per day.

    Pb2Au, the "doesn't build up" was in relation to the question above relating to the CYA build up idea. Of course if you over dose the level increases (builds up) that's just obvious.

  6. Back To Top    #6

    Join Date
    Jun 2011
    Location
    Cape Girardeau, Mo
    Posts
    125

    Re: DuPont Oxone (Monopersulfate) ? For Chem Geek.

    Thanks Chem Geek that was what i was looking for...
    Steve Frakes
    15' X 48'' Intex Metal Frame
    Intex Sand Filter 16'' 2650 GPH
    Taylor K-2006 Test Kit
    BBB and Borated

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •