Nature 2 and OxyShock
- Thread starter TreeFiter
- Start date
The chlorine test strips are usually DPD. I'm not sure what the MPS test strips use for their dye. It might just be a Total Oxidizer test using DPD with potassium iodide so both MPS and chlorine would react with the test strip. You could tell the difference by looking at the chlorine test strip that doesn't react to MPS.
OK, so typically I see high TC when I add MPS, which sounds about right for DPD test strips. But if I let that tub sit, and test it again some time later, I will get a reading for FC. So what changed to cause the reading for FC?
It doesn't seem to be a result of MPS by itself. A few months ago I took a bottle of tap water and added MPS. I capped it and left it sitting on my work bench ever since. I opened it a few times and tested for FC. From the beginning there was none, and I haven't seen a reading for FC since.
But in a tub with Nature 2, if all I add is MPS, I'll see an FC reading.
It doesn't seem to be a result of MPS by itself. A few months ago I took a bottle of tap water and added MPS. I capped it and left it sitting on my work bench ever since. I opened it a few times and tested for FC. From the beginning there was none, and I haven't seen a reading for FC since.
But in a tub with Nature 2, if all I add is MPS, I'll see an FC reading.
I don't use a special strip for MPS. I rely on the TC as an indicator. For the most part, If I have a low or zero reading for TC, I add a hand full of MPS. Then I check again, noting the color change. If the TC reading is still low, I'll add more. Then adjust pH and anything else that is off.
If I am getting a reading for FC, I'll usually add a small amount of MPS and move on. I really wish I could figure out what that FC reading is trying to tell me. Whatever it is, it seems to correlate to sanitizing ability.
I realize this isn't the best method of testing, but my hands are somewhat tied. I keep a TF-100 with me for when I need it, and if something doesn't seem right, I'll check myself, but I've had pretty good luck with test strips, as long as I keep in mind their limitations.
With silver ions in the water the minor component of persulfate reacts with them to form divalent silver and sulfate radicals. Some of these may react with DPD to look like FC though there's probably too little of this to register. So this would only happen when silver ions are present and yes this is partly how the Nature2 system got approved by the EPA with only silver ions and MPS product. See this post for more technical details.
Now maybe MPS itself more slowly reacts with the silver ions to likewise produce sulfate radicals and divalent silver and maybe these react with DPD to look like FC though I don't think the sulfate radicals last very long (not sure about the divalent silver). That's just a guess especially given what you saw with MPS alone not having this effect.
You had reported that using the sodium "stuff" which I believe to be persulfate didn't oxidize bromide to bromine so didn't register FC. I presume that was with water that didn't have silver ions in it. If you were to add persulfate to water with silver ions, I suspect it might produce something (divalent silver ions?) that register as FC due to reaction with DPD.
Now maybe MPS itself more slowly reacts with the silver ions to likewise produce sulfate radicals and divalent silver and maybe these react with DPD to look like FC though I don't think the sulfate radicals last very long (not sure about the divalent silver). That's just a guess especially given what you saw with MPS alone not having this effect.
You had reported that using the sodium "stuff" which I believe to be persulfate didn't oxidize bromide to bromine so didn't register FC. I presume that was with water that didn't have silver ions in it. If you were to add persulfate to water with silver ions, I suspect it might produce something (divalent silver ions?) that register as FC due to reaction with DPD.