Mps Shock-What Happened

[quantumchromodynamics]

There are some references that indicated that MPS can oxidize chloride to chlorine. I don't think that this happens very much in most pools or hot tubs. However, in this case, where the water is hot and the salt level is at 3,000 ppm, it probably creates some chlorine.

This patent indicates that MPS can oxidize chloride to chlorine at a measurable rate when the salt level is elevated, such as in a salt system.

The second order polynomial equation derived from the above data in Table 1 at 29° C. is:

Free chlorine concentration (mg/kg) = (0.040t−0.0024t 2 )×C 0

where C 0 =initial OXONE concentration in mg/kg (for C 0 =6 to 96 mg/kg) and t is time (h).

Reference 1

Reference 2

[waterbear]

There are some references that indicated that MPS can oxidize chloride to chlorine. I don't think that this happens very much in most pools or hot tubs. However, in this case, where the water is hot and the salt level is at 3,000 ppm, it probably creates some chlorine.

This patent indicates that MPS can oxidize chloride to chlorine at a measurable rate when the salt level is elevated, such as in a salt system.

The second order polynomial equation derived from the above data in Table 1 at 29° C. is:

Free chlorine concentration (mg/kg) = (0.040t−0.0024t 2 )×C 0

where C 0 =initial OXONE concentration in mg/kg (for C 0 =6 to 96 mg/kg) and t is time (h).

Reference 1

Reference 2

What I love about this patent and it's claims is that it creates a new market for Oxone by creating a specialty additive specifically for SWCGs thereby expanding DuPont's possible sales of Oxone.The inclusion of carbonate in their formula, while neutralizing the acidic effects of MPS would most likely have a negative impact on pH in the long run by increasing TA. Also, the inclusion of the stabilizer in the formula also probably adds to the apparent increase in measurable chlorine if the initial stabilizer level is too low.

[quantumchromodynamics]

I really don't see the need for the patent, or the additional ingredients. It seems to me that they are going out of their way to make it seem like they have created something new and different. At best, they have figured out that MPS can convert some chloride to chlorine in a high salt environment.

They refer to it as an "invention". I don't see how they have invented anything. All they're doing is mixing different spa chemicals into one product. That's not an invention. I think that the added ingredients are mostly counterproductive. They can be added separately if necessary. They are more likely to mess up the chemistry than help.

The MPS is the only thing that is doing anything, and even that is not necessary. Their primary claim is the creation of chlorine on demand, which can be achieved with sodium hypochlorite.

[chem geek]

They refer to it as an "invention". I don't see how they have invented anything. All they're doing is mixing different spa chemicals into one product. That's not an invention.

Welcome to the world of patent law. The patent office is rather loose about this and you'll see all kinds of products that simply combine different chemicals together -- that is, a new formulation. The bar for "novel" is sometimes quite low. Now if one of the ingredients were uniquely manufactured or synthesized or even if the combination of existing chemicals were formulated with unique techniques, then that would be reasonable. An example of the latter are the sodium cyanurate "instant conditioner" products since creating the slurry wasn't easy and required specific techniques for mixing, pH, time, etc.

[Hillbilly Hot Tub]

This is why I really push people to learn the chemical ingredients in thier chemicals rather than just buying a particular brand name, and check the ingredients (MSDS is the best for this) if it says "new" or "improved" . The "new or improved" may not be what is best for them.

[quantumchromodynamics]

Since they are only showing examples where the salt cell is generating during the test, I am wondering if the MPS is acting directly on the chloride or if it is acting as a catalyst to increase the reaction rate in the cell.

The patent examples are fairly consistent with the poster's results.

[quantumchromodynamics]

I think that the patent example shows some important information.

First, that bromide, at least in the patent example, was not a major factor in creating the higher FC reading. The patent example shows that the FC level rose gradually and steadily over time. If bromide were a significant contributing factor, then the FC would have shown most of the increase almost immediately.

I think that in the original poster's example bromide was probably a contributing factor due to the source of the salt.

Second, the steady increase of FC over time also indicates that MPS was not a significant contributor to the FC reading in the patent example. If MPS were a significant contributor to the FC, then the FC would have shown most of the increase immediately.

Because they used an MPS interference remover (probably N,N-bis-(hydroxyethyl)-2-aminoethane sulfonic acid or N,N-bis(2-hydroxyethyl)glycine)(1), they were able to calculate the level of MPS independently and that showed the MPS levels dropping as the FC increased.

MPS does have and effect on the FC test when no MPS neutralizer reagent is used, so it cannot be completely discounted in the OP's example, especially since they used so much MPS.

I think that the overall conclusion is that MPS can convert significant amounts of chloride to chlorine when added to a salt system while the salt generator is working.

[speculation]MPS might be converted into sulfate radicals in the salt cell. The sulfate radicals could then convert chloride to chlorine radicals, which could then form free chlorine. Reference[end speculation]

________________________________________________________________

Also, note that the poster states that they tested their FC right after adding the MPS and it was 2.0 ppm.

If they allowed enough time for the MPS to mix and react, that would rule out bromide and MPS registering on the FC test as contributing factors.

glennmacph, how much time did you wait after adding the MPS before testing the FC?

[glennmacph]

I put the MPS in 9 hours before the reading-I have my colour Q tester now so accuracy will be better

Should I try something now

[quantumchromodynamics]

Right now, you should maintain a consistent chlorine level. You shouldn't need much MPS.

I was asking about this:

just after the shock I check fc reading and it was 2ppm

How much after adding the MPS, did you get the 2 ppm reading?

What salt are you using?

Are you using cyanuric acid?

[drylandfarmer]

To OP. I add 2 capfuls of refresh when I want to shock my tub. Laminated directions from my dealer, did not do the calculations on the bottle. I have the Genesis system not the Onzen. You stated earlier that you were using 5 capfuls, wondering if it is possible you are using to much refresh (MPS) when shocking.