Terry Arko joins the show once again to talk about non-chlorine shock, specifically the oxidizer product called potassium peroxymonopersulfate, aka monopersulfate or just MPS.
00:00 - Introduction
01:08 - Non-chlorine alternatives
03:06 - Disinfection and sanitization (5 and 3-log reductions)
05:16 - Affinity
07:49 - Oxidation
09:21 - What is non-chlorine shock?
12:06 - Non-chlorine shock vs. combined chlorine?
16:01 - Closing
[00:00:00] Eric Knight: Episode 155 of the Rule Your Pool podcast. This is Eric Knight with Orenda and HASA, and back with me just like it was last episode, Terry Arko. Welcome back to the show.
[00:00:11] Terry Arko: Thanks, Eric. Good to be here again with you.
[00:00:13] Eric Knight: Yeah, thank you. Last episode I learned a whole lot. In this episode we're going to do something a little bit simpler. And I know I'm putting you on the spot, but you're kind of the guru on this stuff. We're going to talk about non chlorine shocks. And in particular I'm curious about the product that we hear a lot about, which is potassium monopersulfate.
[00:00:33] So in this episode, 155, I'm hoping we can describe what that does, how it's different from chlorine, and how it should be appropriately used as opposed to how people misuse it. You ready to go?
[00:00:45] Terry Arko: Let's go.
[00:00:45]
[00:01:08] Eric Knight: Okay Terry, what is non chlorine shock? And how does it work?
[00:01:14] Terry Arko: Basically it's an oxidizer. If somebody is going to go get a product or something that's called non chlorine shock, it's probably going to say non chlorine oxidizing shock. Or non chlorine shock oxidizer. It'll have that word on it. And that's a whole EPA thing because it is not a sanitizer or a disinfectant.
[00:01:36] Perhaps we should start there right away because sometimes there's folks that don't know the difference or that don't know there is a difference.
[00:01:44] Eric Knight: Yeah. What is the difference?
[00:01:45] Terry Arko: Something that is a disinfectant, or maybe more familiar in the pool industry, a sanitizer, that is something that is designed to kill living pathogenic, that's the disease-causing microorganisms. Bacteria, viruses, protozoas, those types of things.
[00:02:05] And that is strictly the role of a disinfectant. When you are disinfecting, you are killing living microorganisms in the water.
[00:02:15] So now we get to oxidation. And sometimes people confuse those two. Oxidation has to do with the breaking down and removal, so it's not a kill, it's a removal of a non-living contaminants like metals and organic material, swimmer waste, oil soaps, dirt.
[00:02:37] Eric Knight: This, this would include nitrogen compounds as well, like urea.
[00:02:40] Terry Arko: Organic nitrogeneous compounds.
[00:02:41] Eric Knight: Okay. So non-living stuff, basically oxidation,
[00:02:46] Terry Arko: All the non-living waste. Which by the way, the only connection there to sanitizing is that those things can interfere with a halogen, chlorine, bromine's, ability to sanitize. So it's important that those things are removed and oxidized in order to get sufficient disinfection or sanitizing.
[00:03:06] Eric Knight: For the sake of the audience, I would like to expand on what Terry just said. Disinfection and sanitation are often used interchangeably.
[00:03:14] Technically speaking, disinfection is a 99.999 percent removal rate within 10 minutes. That's the legal definition. So if you look on a can of household disinfectant like Lysol or 409 or something like that, it will say that on there. To disinfect like for instance, if I spray Lysol on my phone, I'm supposed to let it sit there for 10 minutes.
[00:03:37] Does it actually take 10 minutes? Probably not. But legally it has to say, it has to kill 99.999 percent of pathogens within 10 minutes. That's called a 5-log reduction. That's 5 nines basically. 99.999 And by the way, disinfection is just harmful pathogens. Infectious stuff, right, Terry?
[00:03:58] Terry Arko: Yep. Disease-causing.
[00:04:01] Eric Knight: Right, so sanitation is different, or sanitization is the technical term. That is a 3-log reduction of any living contaminant, whether it's harmful or not. And in swimming pools, the main thing that we're talking about, of course, is algae. Sanitization is a 3-log reduction in 30 seconds. So that is 99.9%.
[00:04:25] So effectively, if you are disinfecting, you're probably sanitizing too.
[00:04:30] Terry Arko: Yes.
[00:04:31] Eric Knight: Okay. Because it's a greater level of kill. So the focus is always disinfection because you know, if algae gets in the pool, it's definitely annoying, but it's not necessarily harmful. What it is, is it's a symptom that you're not keeping up with your chlorination and then other things are probably growing too. And that's a really bad sign.
[00:04:46] If you see algae address it immediately, get on top of things, be proactive. Because you want to make sure that there's enough free available chlorine to handle the actual harmful stuff that can get us sick. I'm off my soapbox. I'm going to turn it back over to you, Terry.
[00:04:59] Terry Arko: No, absolutely. That's absolutely correct. And again as I stated earlier, we have to have sufficient oxidation, and we have to deal with all that non-living nitrogenous organic waste, the metals, whatever else there is. And that's kind of where things get twisted I think sometimes too.
[00:05:16] Eric Knight: Uh, hold on, hold on. I don't want to derail because you just brought something up that's important for the audience to hear that they probably don't hear a lot of. And you and I have talked about this. Let's talk about affinity, Chlorine has an affinity for certain things, meaning the energy level required for it to interact with that substance is lower than something more complex.
[00:05:37] So it has a very high affinity for iron, for instance. It will oxidize iron very easily. But it has an even higher affinity for another halogen below it on the periodic table, which would be bromine.
[00:05:50] Terry Arko: Yes.
[00:05:50] Eric Knight: And when we talked in the bromine episode, sodium bromide, which is something that I'm outspoken against using this in swimming pools because it doesn't go away. That bromide ion is a very attractive target for chlorine oxidation, which creates hypobromous acid, which is a killing agent, but it can't be stabilized by cyanuric acid or anything like that so it gets used up too and creates bromate. But that's a separate topic.
[00:06:14] Oxidants can be, depending on what they are, more attractive to chlorine than certain germs.
[00:06:21] Terry Arko: Right.
[00:06:21] Eric Knight: And that's the problem. Right. Not all of them. I mean, sunscreen is a lot more complex, but I'm not a microbiologist. So I don't want to step out over my skis. But from my understanding, Terry, we should be addressing the oxidant demand so that we have less general stuff for chlorine to get bogged down on so that it can focus on these very important things called germs. Am I correct in that?
[00:06:41] Terry Arko: No, Absolutely correct.
[00:06:42] Eric Knight: I'm not correct. You said no.
[00:06:45] Terry Arko: No, you are correct.
[00:06:47] Eric Knight: Oh, okay.
[00:06:47] Terry Arko: Yes, you are correct.
[00:06:48] Eric Knight: Okay. Got it.
[00:06:50] Terry Arko: I always bring this up when I teach water chemistry classes and I talk about sanitizers and chlorine, and, and I asked the question. I say, do you know why you're putting chlorine in a swimming pool? Now that sounds kind of ridiculous to ask somebody that, but I get a lot of varying answers. And then I'll get the answer to someone say, well, yes, to kill germs.
[00:07:13] Right. Important, that's your primary purpose. You want to ensure the health of anybody using that pool. In other words, you don't want people to get sick from bacteria, germs, viruses, whatever it is. That's why you're putting that chlorine in there. You're putting it in there to disinfect, that's the five log kill, which is great. You know, and if we're killing five log, we're probably killing just about everything else.
[00:07:36] Right? But at the very least, the 3-log, the sanitize. We want to be going after germs. That's our primary purpose. So pool pros or whatever, they're adding it, or operators. And so they're thinking, oh, I'm killing germs.
[00:07:49] Terry Arko: Well, okay. You may not be. Because if you have a lot of buildup of this non-living organic and contaminant, a lot of swimmer waste, you're adding that chlorine. The first thing that chlorine is going to do, as you said, the affinity, let's talk about affinity. It's affinity is going to be to go after those non-living contaminants and act as an oxidizer first. The consuming of chlorine through oxidation,
[00:08:13] Eric Knight: The technical term is reduction. Because if we look at oxidation from a, chemistry perspective, oxidation is the stealing of electrons. We talked about this in a previous episode I did on ORP. I'm going to steal the electrons and I'm going to replace it with an oxygen.
[00:08:28] So the killing agent of chlorine in water is HOCl, hypochlorous acid. I'm going to take the electrons from you Terry, and I'm going to replace it with my oxygen. And I'm going to become reduced to hydrochloric acid. Which, by the way, is what brings the pH back down on a hypochlorite chlorine, which Terry and I have talked about. Which is why you get only a temporary rise in pH when you're using liquid chlorine or cal hypo,
[00:08:53] Terry Arko: Right.
[00:08:53] Eric Knight: I'm getting reduced because my valence is getting reduced. I'm taking on negatively charged electrons. My valence gets reduced. I get reduced as an oxidizer. So when I oxidize something non-living, I can't keep doing it because I am no longer an active killing form of chlorine. I am reduced into chloride, correct?
[00:09:12] Terry Arko: That's correct. Now you've just reduced your ability to sanitize.
[00:09:18] Eric Knight: I've eliminated it.
[00:09:19] Terry Arko: Yeah. Eliminate it.
[00:09:21] Eric Knight: So what is a non chlorine shock? I know I mentioned the product potassium monopersulfate. Is that the only one? Are there others that are used in swimming pools? But I know that's the main one...
[00:09:32] Terry Arko: There are others. Um, there's one in particular, which is called dipersulfate. They all basically do the same thing. They increase oxygen atoms. And they, as you said, they decrease electrons or they take electrons, and they exchange that for an oxygen. Chemically, it's basically a, uh, well, in a sense, it's a form of a peroxide. They call it potassium peroxy-monopersulfate.
[00:10:00] There's hydrogen peroxide in there in a sense, in a dry form. It's like about 42 to 43 percent active.
[00:10:09] Eric Knight: Wow. That's a way more powerful oxidizer than free chlorine. Because chlorine is primarily a sanitizer. Right. It will oxidize, but it's, it just comparatively, it's not meant to really be an oxidizer. When you compare chlorine to something like ozone, there is no comparison. Ozone is a way more powerful oxidizer. Same with hydroxyl radicals from an AOP system.
[00:10:30] Terry Arko: Yes.
[00:10:30] Eric Knight: And a non chlorine shock is going to be a more powerful oxidizer. oxidizer. So what is the appropriate use of this? Because here's the things that I'm seeing when people use it all the time, they're having issues like calcium sulfate scale. Well, we've talked about this because when sulfates get in the pool, um, and we're talking like weekly or every other week use, they're just throwing this in there because they think it's good for their pool.
[00:10:52] And usually it's homeowners. Pool pros for the most part aren't having this issue. But it's homeowners like, well, the pool store sold this to me, so I'm putting this in every week as prescribed. And now I've got these sharp crystals everywhere. It's like, oh, you have very high sulfates.
[00:11:05] Terry Arko: Yeah. That's really hard to get off.
[00:11:06] Eric Knight: Well, you can't really get 'em off
[00:11:07] Terry Arko: very hard to remove,
[00:11:08] Eric Knight: replace everything. Yeah. Yeah. So we're seeing a high elevation in sulfates. What is the appropriate use?
[00:11:14] Terry Arko: I mean, I know the directions for monopersulfate are one pound per 10,000 gallons. I would start there and I would never go more than a pound per 10,000 gallons. So I wouldn't do the whole more is better thing that people do sometimes. You know, like if it's one, I'm going to throw two in. Don't need to do that. Don't do that. There's no reason to.
[00:11:34] The other one is that The directions on these primarily are for weekly use in a pool. Hot tubs, they usually say that, uh, after the use of the hot tub, you should add this as an extra method. And again, in a hot tub, you're using very little, a couple ounces, I think, um, in a hot tub.
[00:11:54] I think the biggest thing is if you're having to shock, if you're having to shock a lot and put a lot of product in, then something else is wrong.
[00:12:03] Eric Knight: Right.
[00:12:03] Terry Arko: And that's a problem.
[00:12:05] Eric Knight: I would think it's really only for a specific thing. And that thing normally is combined chlorine.
[00:12:11] My understanding, and I don't know who's right on this, Terry, I'm hoping you can settle this because I've seen it published both ways. Some people say that non chlorine shock cannot remove combined chlorine, but it can remove the nitrogen precursors of combined chlorine by oxidizing them directly.
[00:12:29] Other people say, well, it can't do the nitrogen precursors, but it will smash combined chlorine. Now I tend to be in the first camp because it makes more sense to me that you can take nitrogen precursors out than dealing it once it's combined with chlorine. But I actually don't know.
[00:12:45] Terry Arko: Yeah. i'm going to absolutely agree with you about the precursors. And that's why I say, it's very important to oxidize on a regular basis. Because hopefully if you do have a regular sort of regiment maintenance of oxidation, you're removing precursors, so you're getting less combined chlorine.
[00:13:05] Eric Knight: Right.
[00:13:06] Terry Arko: Hopefully. That's the goal, right?
[00:13:09] Eric Knight: If you're chlorinating adequately, you may never need a non chlorine shock.
[00:13:13] Terry Arko: Absolutely. If you're maintaining free chlorine always above your combined. In other words, you never allow your combines to get to a place where they're over and above your free chlorine level. You do that. That's it. You're winning.
[00:13:26] Eric Knight: I think we should do another episode on that because we could explore more. I've definitely done a few episodes on chloramines, but I think you and I could go deeper on that chemistry of what combined chlorine actually means.
[00:13:37] Terry Arko: What I've been told from the makers of MPS who I've had relationships with
[00:13:43] Eric Knight: MPS meaning monopersulfate?
[00:13:46] Terry Arko: Monopersulfate, uh, potassium monopersulfate. MPS is a really easy way to say that. Is, uh, that there's also in the oxidation of the product, uh, or as the product oxidized it, it also increases the negative charge of the combined chlorine and that they can be removed by filtration.
[00:14:09] I don't know if that's true. I worked with a company, we sold MPS. And that's part of what I was told. I don't know if, I don't know if there's scientific data or peer reviewed papers or anything on it. Um, that would be something interesting to look up. I was always told and informed that number one, it's very good at removing the precursors. Uh, and that it does deal with the combines and, and we'll remove the combines via filtration.
[00:14:40] And I do know that I had gentleman who contacted me and said that he had figured out a way to remove combined chlorines using potassium monopersulfate.
[00:14:52] And I didn't believe him and I said, okay, tell me. And he said, basically what he did was he would add chlorine neutralizer, sodium thiosulfate first, and knock the chlorine down to zero. And then immediately follow it with a potassium monosulfate. And I went and tried this in a couple of pools, and it worked.
[00:15:12] Eric Knight: Interesting.
[00:15:12] Terry Arko: We knocked the combines down to zero by doing it. And I think theoretically what's happening is
[00:15:17] Eric Knight: It took the chloride bond away.
[00:15:19] Terry Arko: First of all. Yeah. You're neutralizing all the chlorine out. And then now you just have the organics left behind you shock those out. And then you can build your free chlorine from there. And I've done it several times and it's worked. And this was just done by a guy who was operating a pool store. And he came up with it on his own and called me and told me about it.
[00:15:41] Eric Knight: If you are going to reduce all of your chlorine with Thiosulfate and then put in monopersulfate, that's a lot of sulfate. And I don't think that's a viable regular practice. Maybe in a pinch that makes sense. But if you do that consistently, monitor those sulfates because you don't want calcium sulfate in your pool..
[00:15:59] Terry Arko: No, absolutely. You don't want to build up of sulfates.
[00:16:01] Eric Knight: But there's clearly a place for this. It is a bad ass product. There's no doubt about it. It works tremendously well. I don't say the same thing about algaecide products. I don't say the same thing about a lot of stuff out there. But there is no doubt potassium monopersulfate does amazing things in the water. I think it should just be used sparingly. That's my take on it.
[00:16:19] Terry Arko: I agree.
[00:16:20] Eric Knight: Okay, cool. Well, this has been episode 155 of the Rule Your Pool podcast. Terry Arko, thank you once again for being here and sharing a lot of your wisdom that you've learned at least three years in the industry.
[00:16:32] Terry Arko: Yeah, too many I think. But glad to be here.
[00:16:35] Eric Knight: All right. Very good. Thank you all for being here. If you have any questions, you know how to reach us, podcast@orendatech.com. Until next time. Take care.