Nature2 And Mps Non-chlorine Shock

[chem geek]

I believe I finally found a scientific source that would explain the effective use of MPS in hot tubs for disinfection supporting the Nature2 claims and results regarding their "low chlorine recipe". The following is the information and source:

At 77ºF Potassium Monopersulfate provided only 16.8% inactivation of E.coli bacteria in 2 minutes, but at 104ºF it provided >99.9999% inactivation.

SOURCE: Gerba, Charles P. and Jaime N. Naranjo. “Comparison of the Anti-bacterial Properties of Hot Tub Additives and Disinfectants.” Seminar at NSPI Meeting in Las Vegas, November 1999. (I got this from a book of articles by John Wojtowicz in The Journal of the Swimming Pool and Spa Industry (JSPSI) called "The Chemistry and Treatment of Swimming Pool and Spa Water". The specific article is "Survey of Swimming Pool/Spa Sanitizers and Sanitation Systems" by John A. Wojtowicz and appeared in Volume 4, Number 1 of the JSPSI.)

It does not appear that metal ions (e.g. copper or silver) are required for this increase in disinfection capability vs. temperature. By itself, MPS might not quite make it to the 4-log kill in 30 seconds or less required in the EPA test, though it is certainly close. However, standard MPS product contains 3% (by weight) Potassium Peroxydisulfate (aka potassium persulfate) and the use of silver metal ions help catalyze the breakdown of persulfate. This can help reduce the amount of irritation in spas from the MPS product since a primary irritant may be the persulfate.

S₂O₈^2- + Ag⁺ --> SO₄^2- + SO₄^-• + Ag²⁺

Persulfate Ion + Silver Ion --> Sulfate Ion + Sulfate Ion Radical + Divalent Silver Ion

SO₄^-• + Ag⁺ --> SO₄^2- + Ag²⁺

Sulfate Ion Radical + Silver Ion --> Sulfate Ion + Divalent Silver Ion

So the net effect in the presence of silver is removal of persulfate and production of divalent silver that can oxidize organic matter faster than persulfate itself. The sulfate ion radicals are also effective oxidants and I would presume that both are probably fast disinfectants. So the use of silver ions not only reduces irritation, but produces another strong oxidizing and presumably disinfecting agent. [EDIT] Dupont, the maker of the MPS used in most non-chlorine shock products, does not show data supporting the higher disinfection rates even at spa temperatures so there is an inconsistency here. Perhaps the presence of metal ions is required. [END-EDIT]

So that at least explains the Nature2 submission results and makes their “low chlorine recipe” something reasonable. Most people do not follow its recipe literally, however, as it requires a residual of MPS to be measured as present BEFORE you soak while most people seem to be adding the MPS only after the soak. I know that MPS breaks down over time so will see if I can look up how long it is expected to last. I would say that if someone were to use MPS before a soak, that they should wait some period of time so that the potentially irritating persulfate will break down (but I don't know how long that would take -- presumably, not very long). The monopersulfate, which is what Nature2 requires to be measured, should persist much longer. [EDIT] The decomposition rate of MPS at spa temperatures is about 12% per hour so is 90% decomposed after 18 hours (95% decomposed after 24 hours) which is why Nature2 requires testing and addition of MPS BEFORE one soaks in addition to adding more afterwards (since MPS gets consumed during and shortly after the soak by the urea/ammonia in sweat). [END-EDIT]

Since there is such a strong temperature dependence on the effectiveness of MPS as a disinfectant, I'm surprised that there isn't some sort of minimum temperature level required in the Nature2 "low chlorine recipe". Probably anything close to hot spa temperatures near 100F are OK.

It's too bad TinyBubbles no longer frequents this forum. If someone could let him know about the above, that would probably make him feel more comfortable with the "low chlorine recipe" approach he is now using.

Richard

[cplarsen]

Interesting. Nice catch.

[Hillbilly Hot Tub]

I believe I finally found a scientific source that would explain the effective use of MPS in hot tubs for disinfection supporting the Nature2 claims and results regarding their "low chlorine recipe". The following is the information and source:

At 77ºF Potassium Monopersulfate provided only 16.8% inactivation of E.coli bacteria in 2 minutes, but at 104ºF it provided >99.9999% inactivation.

SOURCE: Gerba, Charles P. and Jaime N. Naranjo. “Comparison of the Anti-bacterial Properties of Hot Tub Additives and Disinfectants.” Seminar at NSPI Meeting in Las Vegas, November 1999. (I got this from a book of articles by John Wojtowicz in The Journal of the Swimming Pool and Spa Industry (JSPSI) called "The Chemistry and Treatment of Swimming Pool and Spa Water". The specific article is "Survey of Swimming Pool/Spa Sanitizers and Sanitation Systems" by John A. Wojtowicz and appeared in Volume 4, Number 1 of the JSPSI.)

It does not appear that metal ions (e.g. copper or silver) are required for this increase in disinfection capability vs. temperature. By itself, MPS might not quite make it to the 4-log kill in 30 seconds or less required in the EPA test, though it is certainly close. However, standard MPS product contains 3% (by weight) Potassium Peroxydisulfate (aka potassium persulfate) and the use of silver metal ions help catalyze the breakdown of persulfate. This can help reduce the amount of irritation in spas from the MPS product since a primary irritant may be the persulfate.

S₂O₈^2- + Ag⁺ --> SO₄^2- + SO₄^-• + Ag²⁺

Persulfate Ion + Silver Ion --> Sulfate Ion + Sulfate Ion Radical + Divalent Silver Ion

SO₄^-• + Ag⁺ --> SO₄^2- + Ag²⁺

Sulfate Ion Radical + Silver Ion --> Sulfate Ion + Divalent Silver Ion

So the net effect in the presence of silver is removal of persulfate and production of divalent silver that can oxidize organic matter faster than persulfate itself. The sulfate ion radicals are also effective oxidants and I would presume that both are probably fast disinfectants. So the use of silver ions not only reduces irritation, but produces another strong oxidizing and presumably disinfecting agent.

So that at least explains the Nature2 submission results and makes their “low chlorine recipe” something reasonable. Most people do not follow its recipe literally, however, as it requires a residual of MPS to be measured as present BEFORE you soak while most people seem to be adding the MPS only after the soak. I know that MPS breaks down over time so will see if I can look up how long it is expected to last. I would say that if someone were to use MPS before a soak, that they should wait some period of time so that the potentially irritating persulfate will break down (but I don't know how long that would take -- presumably, not very long). The monopersulfate, which is what Nature2 requires to be measured, should persist much longer.

Since there is such a strong temperature dependence on the effectiveness of MPS as a disinfectant, I'm surprised that there isn't some sort of minimum temperature level required in the Nature2 "low chlorine recipe". Probably anything close to hot spa temperatures near 100F are OK.

It's too bad TinyBubbles no longer frequents this forum. If someone could let him know about the above, that would probably make him feel more comfortable with the "low chlorine recipe" approach he is now using.

Richard

Thanks Richard for taking time to search for this info. I think your concern about using MPS after a soak is being somewhat addressed, although without reasoning from them, by Zodiac by coming out with Cense. This is MPS with a scent added to it, so people are going to want to add it before spa use. Plus if people are testing their water for MPS, they should have a reading although chlorine will effect this reading. Most people keep their tub at 99 or higher, so I would not think this would be an issue. My question would be for the pool users that use the nature 2 vessel at the lower tempretures...?

[chem geek]

I know the Nature2 instructions say to test for MPS before soaking and to add some if not there, but from what I've read from most posts, most people add the MPS after the soak just as they do with chlorine, but don't seem to test for a residual before soaking. It's good that Zodiac came out with an "incentive" to have MPS before soaking. Sounds like Zodiac is trying to do the right thing here -- good for them!

As for Nature2 in pools, I don't think Nature2 is sold in a low chlorine recipe for pools. Pools still need chlorine (or bromine or PHMB/biguanide/Baqua) and cannot use MPS alone as a fast-acting sanitizer. It still apparently is somewhat of a sanitizer so is better than nothing, but it doesn't last very long and I don't believe the once a week dosing would work even for preventative (slower-acting) sanitation because monopersulfate is decomposed by sunlight much faster than stabilized chlorine (a decomposition rate in sunlight of about 20% per hour -- about 10 hours for 90% decomposition; even without sunlight it decomposes at around 4% per hour -- about 56 hours for 90% decomposition while for spas it's much faster decomposition). Nature2 for pools is really used mostly for the metal ions so can be seen as an insurance policy where the copper prevents algae and the silver helps to prevent runaway bacterial growth. Personally, while I can see the benefits of Nature2 for spas, especially when using chlorine if one is not diligent or if one wants to use mostly MPS, in pools this can get pretty expensive (due to the Nature2) and there are other alternatives to ensure one doesn't "forget" to add chlorine -- like using The Liquidator.

Richard

[limulus]

As I posted in another thread, I've elected to sanitize a cedar hot tub we're installing at a mountain home with chlorine. I had originally planned to use bromine. I have lots of MPS and 2lbs of Leisure Time Spa 56 Chlorinating Granules. Since we won't always be around, simplicity is a must. Today, I ordered a Nature2 cartridge.

Our tub has an ionizer built in. However, it is a copper-only ionizer made by Pioneer. I've been able to determine that copper is really only good for algae and not bacteria or viruses. For a mineral system to be effective at all against bacteria and viruses it needs silver. I see lots of references to silver in the discussions about Nature 2. However, I don't know what else is in it. I have to assume there is some copper and/or zinc. If I run my ionizer and there is also copper in the N2, I will have a very high copper content. I do have a Taylor copper kit which will verify this.

The N2 site doesn't really say exactly what is in the cartridge. This is what I've read on their site:

"In pools, silver and copper work in conjunction with the small level of chlorine to destroy bacteria and other organics. Nature2 Spa combines silver, and other trace elements, to effectively sanitize even at the higher water temperatures."

It specifically mentions copper for pools, but not spas. It does mention trace elements, which I'm going to assume will be some copper. I think I'll use my Taylor copper kit to keep an eye on the copper levels and if it gets too high, I'll turn the ionizer down or completely off.

[roromissd]

Our dealer specifically told us to add MPS after soaking, not before. We have the silver ion cartridge and ozonator. Are they wrong? It seems to work this way. When I test, everything comes out right.

Anne

[chem geek]

Our dealer specifically told us to add MPS after soaking, not before. We have the silver ion cartridge and ozonator. Are they wrong? It seems to work this way. When I test, everything comes out right.

Anne

The Nature2 owner's manual shown here explicitly says that you must have a residual of measured MPS in the water when you soak and that generally means adding more before you soak and probably more afterwards as well. I'm not recommending this -- I'm just telling you what Nature2 is recommending, probably in order to pass EPA sanitizer tests.

Richard

[HuMan123]

Sorry to dredge up an old thread, but this addresses some of the questions I have on my 225 gallon Hot springs Jetsetter tub.

It has 24/7 ozone/recirc, Hot Springs "Nature2 silver ion stick in filter and I am using Spaguard products of "Spa Shock-Oxidizer (31% Potassium Peroxymonosulfate) and Enhanced Shock (58.2% Sodium dichloro-s Triazinetrione)

I use MPS after every use in the amount of 1Tbsp per hour of bather load at 99 degrees and use 1.5 Tbsp of the 58.2% dichlor once a week. I am trying to put in enough MPS to have a reading 24 hours later when we soak again (new tub, high usage).

After reading this post I see that (quote from above - [EDIT] The decomposition rate of MPS at spa temperatures is about 12% per hour so is 90% decomposed after 18 hours (95% decomposed after 24 hours) which is why Nature2 requires testing and addition of MPS BEFORE one soaks in addition to adding more afterwards (since MPS gets consumed during and shortly after the soak by the urea/ammonia in sweat). [END-EDIT])

MPS appears to decompose fairly quick and I wonder if I am chasing my tail to "always" keep a maintained level of MPS and should just add some after and then 30 minutes or more before use. I read conflicting info on whether MPS residual needs to be maintaned 24/7/365. One thought says "yes" as MPS works with silver ion to be a sanitizer and another says the silver Ion is sanitizer, but needs MPS to oxidize bather waste which would be accomplished by adding after usage and before (not necessarily in between?)

The whole subject is vague to me as I read the low chlorine recipe from Nature2 and it says to add before and after leaving me to read between the lines for the "in between residual" Any help or links would be greatly appreciated as while I am now maintaining an MPS level 24/7/365 to be sure it is causing me to use more MPS product and possibly creating high sulfate level where I can see minor white spots on the black step after water dries.

I even called Zodiac and spoke with technical support on specifics and it seemed the conversation changed as I asked different scenarios. I really did not get a good feeling that they were knowlegable on my questions.

If anyone has an approximate chart of MPS PPM to Tbsp in gallons of water I could use that as well. I have found where a Tbsp in 250 gallons would equal 12PPM and also found 20PPM for same rate. I have Taylor kit with K-2042 interferance reagent too and that is not working for me. 1st batch sent was frozen and next batch provided very high cc readings. Taylor tech support has verified my reagents are fresh and the process I am following is sound, yet not working for me. They have escalated my issue to a higher level and I am awaiting the response. I asked Zodiac what PPM level I should have with the Taylor process to match "OK" on an MPS test strip and was told 14-15PPM. Don't know if this is valid info or if it matches my strip until I figure out why Taylor process is not working.

Thanks for reading!

[chem geek]

The MPS is both an oxidizer and when used in conjunction with silver ion it is also a disinfectant. Silver alone is not a complete disinfectant and it is also slower. It's the combination of silver ion with MPS at hot spa temperatures that results in fast disinfection comparable to chlorine or bromine. So technically, you'd want to maintain an MPS residual in between soaks to ensure disinfection, but if the MPS did go to zero at least you have the silver ions there to inhibit some bacterial growth.

1 tablespoon of typical MPS which is 43% potassium monopersulfate (the rest is mostly the other components of the triple salt -- potassium sulfate and potassium bisulfate) in 250 gallons would be around 0.68 ounces weight (given typical density of product) or 14.175 grams in 946 liters so 15 mg/L but the product is not pure triple salt so the 12 ppm sounds about right if they are talking about the triple salt (and not the MPS portion alone).

[fishn4life]

I really wish there was a table of some sort....

There is a wealth of information on this forum, unfortunately when it comes to this topic it seems everyone has there own "ballpark" method of measuring.

Leisure Time Renew states this on their website:

After Each Use:
1. Turn on filtration system.
2. For each 250 gallons of water, add 2 ounces directly into spa water.
3. Run filtration system for 15 minutes with cover off.
4. Repeat process once a week to help maintain clear, odor-free water.

LOL, it says repeat once a week, but starts by stating "after each use."

Renew also has buffers already mixed in so a different brand oxidizer might be a different dose?

If you find a "miracle chart" please share...

[chem geek]

The rough rule-of-thumb is that every person-hour of soaking in a hot (104ºF) spa needs around 3-1/2 teaspoons of Dichlor or 5 fluid ounces of 6% bleach or 7 teaspoons of non-chlorine shock (43% MPS) to oxidize bather waste. With an ozonator, the required amounts may be half or less.

As for how much is needed to maintain an MPS level in between soaks, that's something you just have to see for yourself. Even the above rule-of-thumb is just a starting point. Every tub is different so you need to measure and adjust accordingly. The good news is that once you figure out the rough amounts, they stay reasonably constant. So figure out how much oxidizer is needed per person-hour of soaking and how much is needed in between soaks per 24 hours (i.e. background loss rate).

[HuMan123]

Your rule of thumb works pretty close for my tub. With 24/7 Ozone and Nature2 I find using 1 Tbsp per hour of soak gets me through to the next soak 24 hours later. I am not sure what I will need to do when I go away for a 3 day weekend or week vacation and still looking for good data.

I asked my dealer specifically about having a residual of MPS at all times (24/7/365) and they say it is not necessary. I believe what Chem Geek writes here more so I am following that, but wish I could find it in print besides this forum because with their knowledge of this I don't believe they would believe forum posts.

Why can't Nature2 or Dupont specifically state this and not make you read between the lines of their products?

[chem geek]

The Nature2 manual says to test before each use and add MPS if it's too low and then after each use to add more MPS. They do not adjust the amount added afterwards for bather load, even though they should. They do not say one needs to maintain the MPS in between soaks -- for "every day" the manual says "Run spa according to recommendations supplied to you by the manufacturer of your spa." They probably don't care with what happens to the spa in between soaks and are only focussed on having proper disinfection during your soak and to some degree handling your bather waste. With the silver ions, even with the MPS getting to zero there is at least some protection against runaway bacterial growth.

I wouldn't worry about it nor try and convince your dealer. With chlorine it's very clear one needs to maintain it's level in between soaks, but silver ions with MPS is a dual system so it's not so clear cut.

[HuMan123]

Thank you for the reply! I agree with you 100% and only wanted to bring to the dealers attention if there was specific written directions from the OEM of these products. I showed them the "low chlorine recipe" that is in the Nature2 box and they were surprised to read of the requirement to test and add "before" soaking. The comment was "I would not want to add chemical just before soaking" which I replied that I did not want to either and was trying to add enough 24 hours earlier to make this unnecessary.

Problem with that is with the degradation of the MPS over time it is making you use a lot of the product which is probably not good for many other reasons.

[chem geek]

The reason that the Nature2 manual says to measure the MPS level before the soak and add more if it's low is the same reason that chlorine instructions say to measure and maintain a chlorine level (with the implication that this means before a soak as well). The EPA has specific tests for disinfection and they establish minimum levels of disinfectant to meet the kill time requirements so technically they want you to maintain such levels, especially when bathers are present. This is to prevent person-to-person transmission of disease.

Now in practice, such concerns are most relevant to commercial/public pools where such transmission is a much more serious affair since one person can affect dozens or more (Crypto outbreaks can affect hundreds though that's mostly because chlorine at normal concentrations is pretty much not effective against Crypto). Soaking with a strong oxidizer won't be as pleasant. With MPS, it can be irritating though the silver ions do react with the most irritating minor component in MPS so that it is not so irritating. Chlorine will not only oxidize, but will combine with sweat and urine to form monochloramine which can smell somewhat if it gets too high. So we usually talk about starting a soak with 1-2 ppm FC, but technically it is unlikely for the chlorine to last during the entire soak (unless it's very short) and instead it will get converted to monochloramine so while still inhibiting bacterial growth, it's not a fast killing disinfectant and not a strong oxidizer. Adding chlorine after the soak then oxidizes the bather waste and re-establishes the strong chlorine fast disinfection.

It is a violation of law to not follow the label instructions, but no one is going to go after residential spa or pool owners for not doing so unless they flagrantly do something that could harm others like improperly dispose of large quantities of chemical that affect the environment. It is again the commercial/public spas and pools where such enforcement of proper usage is done. This is very similar to how commercial kitchens are regulated while residential kitchens are not. Manufacturers of pesticide chemicals have to follow FIFRA regulations and tell you the officially correct thing to do in order to make disinfection claims, but you as an individual in your home are pretty much responsible for what you do.

So if you don't want to have the MPS level as high at the start of your soak, that's up to you. If you're not soaking with strangers whose diseases you do not want to share, then your risk is low. Bacteria double in population in 15-60 minutes so won't turn your spa into a mess during the normal time of a soak. It's a judgement call.

[Scalawagy]

The nature 2 directions also state, that dichlor can be used instead of Mps.

Any thoughts on this?

Would a person still want to switch to bleach after a while?

would letting the fc level drop to 0 between uses be a bad idea?

Ken

[chem geek]

If you use only MPS with Nature2, then the water can get dull/cloudy since MPS doesn't oxidize all the same chemicals that chlorine does. So normally for a minimal chlorine approach one uses Nature2 with MPS and then shocks with chlorine once a week or so. If you use Dichlor instead of MPS all the time, then what's the point of having the Nature2? Using chlorine defeats the purpose of being non-chlorine or minimal chlorine. I suppose having the silver ions from Nature2 might help prevent the water going south if you forget to dose and the chlorine gets too low, but we don't have enough reports to know if it really works that way. I know that ozonators won't always keep a tub from going south.

As for using bleach, yes you could use Dichlor first and then switch to bleach, but again then what's the point of the Nature2 except possibly as some sort of insurance if the chlorine gets too low?

[NickJ]

Richard, (Chem geek)

Thank you so much for sharing your incredible knowledge on this forum as well as the TFP forum.  I have a few questions I hope you will answer:

1. Does a silver ion generator (silver and copper ions) accomplish the same thing as using a mineral approach like Nature2 and should one follow the same MPS regimen before and after use to get that benefit from a silver ion generator?  One drawback it seems to me would be the inability to "measure" the silver ions (for most of us) so adding silver (Nature2) ions every few months would seem to provide some assurance they are actually present.

2. Is maintaining PH important for silver ions in the presence of 104 degree water with MPS to work?  In my case we almost never use our Jacuzzi and have always drained it and reestablished bromine, PH and TA before using it again (a real pain!). My goal is to find a solution that would keep the water safe (germ free) for months without having to balance PH and TA and bromine levels constantly so I wouldn't have to drain it the next time we decide to use it.  I would just reestablish bromine level and balance PH and TA before each use. Would that work?  Would I still need to add MPS before and after use if I reestablish the bromine (or chlorine) level each time? I've read bromine can't be used with Nature2 so is that true of a silver ion generator too?

I guess that was more than 2 questions.

Thanks,

Nick