Oxidation & Sanitation: The Six Faces of Chlorine

Sometimes, to master the science of pool care, you’ve got to rewind all the way to the fundamentals — and that’s exactly what Wayne does in this nostalgic, knowledge-packed Throwback Thursday episode of the Talking Pools Podcast.

This week, Wayne strips away the marketing fluff, the industry noise, and the high-tech gadgets to return to where it all began: Chlorine 101. He breaks down the true difference between oxidation and sanitation, revealing why so many pros get it wrong — and how that mix-up can mean the difference between crystal-clear water and chaos in a bottle.

From sodium hypochlorite to trichlor, from cal hypo to chlorine gas, Wayne dives into all six types of chlorine, explaining how each one behaves, reacts, and—let’s face it—sometimes misbehaves in a pool. You’ll walk away reminded that this simple element is anything but simple.

Whether you’re a seasoned pool tech who’s been around since chlorine came in glass bottles, or a rookie trying to wrap your head around free vs. combined chlorine, this episode will reignite your respect for the basics that keep every pool sparkling and every customer safe.

💧 Because even the pros need to go back to where it all started sometimes — the chlorine.

Transcript

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Good day everybody. Happy Thursday. Happy 2024 if you're listening to it then. This is Wayne at Talking Fools um podcast among the group of insanely intelligent and wildly hilarious people who work with me on the Talking Fools podcast. Happy New Year to you guys too. So what are we gonna talk about? First one for 2024. Well, um thinking over all the stuff that I've talked about since um I came on board in the fall of 2022, um I know I've repeated a few things and and and rambled and ranted and all the other stuff. And and yeah, and that's fine. But but you know, returning to the basics, it's probably not a bad idea, quite honestly, because we all need refreshers, we all need to be reminded of of how everything works and everything comes together. So what I'd like to do, at least for the next few podcasts, um, is go over some of the some of the basics that uh service text should be wary of. And I think the very first one um is not water balance, believe it or not, but is simply sanitation and oxidation. Um there's so much involved with that nowadays that it's it's it's very confusing. Let's put it like that. So what I want to talk about and specifically focus on right now is chlorine. Because, you know, let's let's face it, gang, chlorine is it uh as far as I'm concerned, um, when we're talking about sanitation and oxidation, effective sanitation and oxidation. And the assumption along with that is that the person who's dealing with the chlorine product knows what he or she is talking about, which is again important, critically important. So, what we're gonna do today is talk about chlorine, uh, the good stuff, the bad stuff, etc. And then upcoming podcasts will be talking about alternative methods and and things like that, and what you should look out for, and testing, and and all sorts of other nice, neat things that that I have been instructed to talk about uh from the powers that be here. So um let's go ahead and start right off. So, you know, the title of this particular podcast is that chlorine is your friend. It's not an enemy, it's not something to be scared of, it's not something to be uh leery of. Uh, it is there for a reason, and the obvious reason is for sanitation and oxidation. And remember that there are only two products that both sanitize and oxidize at the same time. Only two. Period. End of story. Uh of course, chlorine is one of them. And the other one is bromine. And we'll talk about bromine down the road, but but I'm going to concentrate on chlorine today. So when you're when you're purchasing chlorine, you're getting um a one-two punch. Uh, you're you're getting two two vital important um aspects of making sure your water is safe for for your customers. So obviously, I mean all know sanitation is is the killing of things, uh bacteria, um uh nasty critters, organisms, things of that nature. Oxidation, on the other hand, is simply the removal by oxidizing um organics in the water that get in there. So, so what do I mean by that in English? Well, anytime we get into a pool, anything that comes off of our bodies uh is considered organic in nature. So we're talking hair, skin, oils, and any lotions, fabrics from bathing suits. Hopefully, you're wearing one. Um if you let your and your your pets in the pool, you know, dog fur, not a cat, cat in a pool is kind of redundant. Funny, but redundant. Um, leaves, twigs, grass clippings from landscapers. Ooh, we service people hate them, don't we? Um things like that, uh, algae that might get into the pool. So anything of an organic nature needs to be oxidized or burned off, and that's what oxidation is. Chlorine does both, so does bromine, but we're gonna talk about chlorine today. So when we talk about chlorine, it's also important to know a couple things. That of all the the six current forms, that's six now, six, see five and one is six, the six different kinds of chlorine that are available, um, not necessarily what you use, but that are available, each have their own little um idiosyncrasies, their own little things that that make them different from any of the other forms of chlorine. So, what we're gonna talk about is all those six forms of chlorine, their advantages, their disadvantages. Um, which should you use in what kind of a situation? What's recommended, what's not recommended, things of that nature. So, you know, um sit down, buckle up, raise your uh tray tables to their upright and locked position, and let's go ahead and take off. So, the very first form of chlorine that we're going to talk about is chlorine gas. Uh, and when when we're talking chlorine gas, it it it is uh also something that's very dangerous to work with. Uh, it's also known as mustard gas. Killed a whole lot of people in World War One, um, the various factions in World War I. No, I was not around then, although sometimes I feel like it. Uh, but with uh chlorine gas, with mustard gas, it is it is very dangerous to work with. That's why you don't find it too terribly often in the country anymore, at least in the US uh and and most of Canada. Um the the health departments of the various states and provinces are very um wary of people who were who work with chlorine gas. And you usually need some kind of a additional certification when you're talking about um dealing with chlorine gas. But back, say about oh geez, uh 40-ish, 50 years ago, 60 years ago, chlorine gas is very popular uh because it's cheap. It's cheap to create, uh, it's cheap to uh uh administer into the flow of water. Um and and that's what made it very, very, very attractive. Um I know that there was a couple of um swimming holes. Um that's the only way to describe them in the Baltimore area. Uh actually it was a swim club, one it was called Milford Mill Swim Club, which was essentially a quarry back in the day, and they filled it up with water and they used uh chlorine gas as the primary sanitizer. And I remember seeing the tremendously large chlorine gas tanks, um, not terribly far from each of the pool locations. They had like four or five pools uh on the property. Um, and of course, back in that back in that time I had not been in the industry, so you know I could have cared less. All I could care about was getting into the water, getting into the pool. So, um what happened is that the chlorine gas, although terribly efficient, okay, horribly efficient, the the downside is, of course, that it's going to be dangerous to work with. It will kill you if you don't know what you're doing. And honestly, back back in the day, you really shouldn't use chlorine gas for very, very, very, very, very large pools, like say 200 to 250,000 gallons or higher, because of the cost of the high capital cost, the actual tank, not the cost of the gas itself. Not because of the actual cost itself, but the actual handling of the equipment. Um there are very specific regulations that various health departments will require that you um follow in order to make sure that the health department knows that you know what you're doing. Uh at least you pretend that you know what you're doing. Yeah, let's talk about the good stuff about chlorine gas. Um, it is chlorine, period. End of story. It's 100% active strength. It is chlorine. Um the downside, not the downside, but the opposition to that, is that the pH of that particular kind of chlorine is zero. It is as acidic as you can make it. Um, although in the pH world, yes, there are negative pHs, but you don't see that in our industry at all. You see that more on industrial and and chemical side. But the pH is zero. So the use of chlorine gas will, of course, pull down pH and indirectly pull down alkalinity, too. So you could be causing some issues, some some problems. Um, the other thing, too, is that uh chlorine gas is not used as much anymore. Uh again, here in the Baltimore area, it's no, you don't see it at all. And I only know of a couple facilities in the country that actually use chlorine gas still to this day. So, uh, how do you handle it? Well, just like any of the chlorine, it's injected into the flow of water, it goes back into the pool and does its does its thing, sanitizes and sanitizes and oxidizes. Sorry for the coughing, guys. Getting over a really bad sinus infection. So um deal with it. Um so uh when you're when you're adding chlorine gas, however, chlorine gas, it's it's a gas. Okay. And what does that mean? Well, in English, a gas means that it will gas off. And it will not hang around in the water terribly, terribly long. So you constantly need to add chlorine the whole time that you're using this particular product. So you need to be very, very careful with what you're doing. Now, since chlorine isn't used so terribly much, um uh because of its potential issues with health and death, um, why is it still around? Well, believe it or not, there's actually people, crazy people, as far as I'm concerned, people who use um uh chlorine gas as kind of like a drive-by. I did that's really the only way to describe it. Um out in California, uh, you might have heard for those of you out there, um, you might have heard of uh people called uh uh chlorine gas shooters. And basically what it is is that a person carries a tank on their back of chlorine gas and has an attachment on it, so they stick this this nozzle into pool water and add X amount of chlorine gas to shock the pool, shoot the pool. Um, this is obviously dangerous and I believe in most counties in California, hopefully somebody can correct me, uh, horribly illegal if if caught uh because you could be killing yourself, you could be um hurting other people if for some reason the chlorine gas escapes the tank, etc. So it's it's not used that much uh anymore. Back in the day, yes, nowadays, no. In 2024, no, absolutely not. So let's move on to the second kind of chlorine. This one you're probably more familiar with, at least I hope so, and that's sodium hypochlorite. So chlorine gas is a gas, sodium hypochlorite is a liquid, aha! Also known as bleach generically. Um you know, the brand names like chlorox and things like that, and and in Canada it's um I'm probably pronouncing this wrong because of X, J-A-V-E-X. Uh, these are uh laundry-grade sodium hypochlorite uh products. Now there's a difference between laundry-grade uh sodium hypochlorite and pool-grade sodium hypochlorite. Let me talk about I'll explain that in a couple minutes, but let me talk about generalities. Uh sodium hypochlorite is a liquid, it's pretty effective as a shock. Uh, you're pouring liquid into liquid, pretty much an instantaneous mix. Its active strength is about 10 to 12 percent. Really depends on how long it's been sitting around before it's bought. Um chlorine gas chlorine gas, right? Sodium hypochlorite is manufactured at around 22 to maybe 24% strength. And then by the time it's actually poured into containers, delivered, things like that, and put into use, it's weaned its way down to 10 to 12 percent. Is that 10 to 12% still good? Yeah, it's still good. Uh uh actually, uh it's it's a very good product. Um the problems with with sodium hypochlorite, um, one is that unlike chlorine gas, which has a zero pH, sodium hypochlorite, and in fact all the hypochlorates, have very high pHs. Uh, in this particular case, depending upon the manufacturer, it could it could be 11 up to 13. And remember the pH scale only goes to 14. So it's really, really up there. So over overdosing will have an um increasing effect on pH and a slight increasing effect on alkalinity. So you have to be really, really, really careful. Um, now let's talk about the difference between laundry grade and pool grade sodium hypochlorite. So remember earlier I talked about the difference between pool grade sodium hypochlorite and um laundry grade. Here's what's important about this. Laundry grade sodium hypochlorite, like the stuff you buy in your grocery store, is anywhere from four to five percent strength. So it's halved as far as uh total chlorine content is concerned. Also, pool grade, excuse me, uh, laundry-grade sodium hypochlorite, it's not as well filtered as pool grade is. So you have a lot of inert material in that particular product. I get the I get the question, or used to get the question a whole lot, can I use you know Clorox, laundry bleach in my pool? Well, yeah, you could, but you'd wind up um having to use twice the amount than if it was an uh pool grade uh of sodium epicoric, and then the amount of inert material increases uh TDS levels. You can talk about TDS when I talk about water balance, so I'm not gonna go into it right now. So um again, the good thing about it, instantaneous mix, um, it's a it's a great shock. The things about it is that it does it, it's a very high pH, it does degrade naturally. So even though you might use it at 10 to 12 percent, by the time you get around to it, it could be lower. So you have to be very careful. As a service person, there are ways to measure the strength of sodium hypochlorite. Several test kit manufacturers um do make kits that will tell you uh the what the exact percentage of the product is. This is really good for um retailers and distributors who actually manufacture uh sodium hypochlorite on on their property and then you know deliver it out to their customers. Um bleach can sodium hypochlorite can lose its half of its strength in three months. So sitting around, you know, just doing nothing uh is going to degrade it down naturally. So you have to be really, really careful of you know, must use by dates, you know, that kind of thing, that you're using the the correct strength sodium hypochlorite. Um so we've got one extreme to the other. We've got chlorine gas at a zero pH, we've got sodium hypochlorite at a 11 to 13 pH. What are all the other ones? Well, the other form of calcium hypochlorite, uh the other form of excuse me, chlorine, it's calcium hypochlorite, calhypo. Everybody knows good old calhypo. Uh a granular product. Uh again, it's a hypochlorite, so that means it's gonna have a little high pH. Depending upon who makes it, it can be as low as 8.5 pH or as high as uh almost 12, 11.8 pH. Depends on the manufacturer, so you need to check your STS sheet to see what the pH of the product is. Again, depending upon the manufacturer, it's gonna have a uh variance on uh how much chlorine is actually in the product. And generally speaking, anywhere from 45 to 78 percent of calhypo uh is as cl contains chlorine. Now I have heard of, I haven't seen, but I had heard I have heard of 80% and 85% cal hypo. Having not been able to confirm that or see it anywhere. Uh, one of you might want to pop me an email at talkingpools.gmail.com. Let me know what's going on if you have seen that. But generally speaking, 45 to 78 percent is what the strength of Calhypo is. Um again, it's a granular product, although a few years ago they developed tablets, calhypo tablets, uh, that you can fill into an erosion feeder designed for cal hypo tablets, not for anything else. Of course, tablets will slowly release uh small amounts of corn into the flow of water back of the pool. Um, you have to worry about sometimes turbidity issues, sometimes you have to um um uh be careful with um all these inert materials that uh are around uh that could cause an increase in um in in TDS. So be very, very careful. Also, if you overuse cal hypo, you can cause it you can cause some turbidity issues, some cloudiness. But if you you know if you follow the instructions and you add the right amount of chlorine for whatever it is you're trying to do, you're good to go. Okay. So let's go on to the next one. Another hypochlorite product. So, what does that mean, class? Yes, Tommy, in the back. Yes, Tommy, what do you say? Well, that means it's high chloride, high pH. That's exactly right, Tommy. Thank you. So, bad imitation, sorry about that. Um, so we've got uh the fourth one called uh lithium hypochlorite. Now, hypochlorite, okay, so we're talking high pH product. Um, depending upon uh well its source, almost uh 10.8 is is what the what the common pH of lithium hypochlorite is. Lithium hypochlorite has a very distinct and specific purpose. It's a very fine uh granular, almost a powdery kind of product that when used um is is a great shock in vinyl liner pools. Whether the vinyl liners in ground or above ground, doesn't matter because it dissolves almost instantaneously. Okay, almost instantaneously. Uh it's one of the safest forms of chlorine to deal with. Uh it's it's completely soluble in water, just like I said. Um you don't have to pre-mix it like you do cow hypo sometimes or sodium hypochlorite. You just you know add it right into the water. The disadvantages to using lithium hypochlorite is that it's very pricey and almost non-existent, believe it or not. Um, a few years ago, the only location you could get lithium hypochlorite from was from some um mine in China, something like that. Uh now it may have changed um since I last looked into it, but back a few years ago, you could it was very rare to be able to get lithium hypochlorite. And if you were able to get it, boy, did it cost a pretty penny to um um to to to purchase. Um that's why it's not even carried around much anymore. Uh, but it still is a good product. Okay um if you can find it, that's that's the big thing. If you can find it. Now, those the these four forms that I've already talked about chlorine gas, sodium hypochlorite, calcium hypochlorite, lithium hypochlorite, uh we all know. Them as unstabilized chlorine, which means that if you added one part per million worth of any one of those four products into an out uh a pool outside bright and sunny day, that one part per million is going to dissipate out in about 10 to 15 minutes, depending upon where you are. So we want to keep chlorine longer in the water, and so uh we have two products that are chlorine that kind of help with that problem. Um, the first one I'm going to talk about is actually trichlor. Trichlor is a tablet um that comes in a variety of like one-inch tabs, three-inch tabs, depending upon what kind of erosion feeder you need to add it to add the trichlor to the water. Um the the thing with uh this particular form of chlorine, trichlor, it's at the um opposite spectrum. It almost resides there with chlorine gas as far as um uh pH is concerned. It's anywhere from 2.8 to 3.5, yeah, depending upon who makes it. It's all it's also about 99% active strength. So it's very little um uh inert material in there. Um, one of the materials that are part of trichlor is cyanuric acid. Now, um, when I talk about cyanuric acid, we all know what that does. It extends the life of chlorine and water, usually anywhere from four to six times longer than if it wasn't there to begin with. So I'm not gonna talk about cyanuric acid today. This is this is not a cyaneuric acid podcast. Later on, maybe, yeah, but not now. So trichlor tablets, very, very convenient, um, slow dissolving. Um it's convenient, you just plop the tablet again in the floater, the feeder, whatever. Um, and I'm gonna do a finger wag right here. Um, never, never, never, never, never, never, never, never, never did I say never enough, but never put a trichlor tablet or the other tablet uh chlorine by chlorine wise, which is dichlor, in a skimmer. A skimmer is not designed to be a chemical um um uh dispersing pro piece of machinery. It's it's it doesn't dispense chemicals. It's not designed to do that. It's designed to skim surface materials off the pool. There's a couple exceptions to that, but you should never really put a trichlor tablet in a skimmer. One, the low pH makes it so acidic that it's going to destroy the skimmer basket. That's called common sense. Okay. So big time, that's why you shouldn't put it in there. Now, the thing with uh trichlor is that it also has a tendency to to pull down alkalinity uh in addition to pH because it has such a low uh pH product. Um it now with with cyanuric acid content uh for every uh two three-inch tablets of trichlor, okay, for every two uh every three two three-inch tablets, and that's not quite eight ounces, you are introducing about seven parts per million of cyanuric acid into the water per 10,000 gallons of water. So I'll let that sink in for a moment, and and while it's sinking in, I think most of you go, oh shit, um it's gonna bump up cyanuric acid, and that's exactly right. Um, to the point where there are issues um with high cyanuric acid levels that I am not going to get into. Um our our our good friend Rudy uh Snakewitz has more knowledge about that than than I ever will. Um but it high cyanuric acid levels can cause some problems. Now, the other form of of stabilized chlorine, which is what trichlorid is, uh, is called dichlor. Um and what dichlore is, it's essentially the same idea as trichlor, except there's a couple a couple things that make it unique. One is that it's almost almost, but not quite, pH neutral. Neutral pH is seven. And dichlor, depending upon who makes it, it's around 6.7, 6.8 pH. So pretty darn neutral. Now, as far as cyanuric acid content is concerned, depending upon who makes it, again, for every two three-inch tablets, you're adding anywhere from four to six uh parts per million of cyanuric acid per 10,000 gallons of water. So, again, it's going to build up over time, particularly in areas where you're using stabilized chlorine a lot. Uh, where I am, the Atlantic area, Florida, things like that, can become a problem. So you need to be aware of that. So, testing frequently, okay, is is the key to uh making sure that the cyanuric acid level isn't that terribly high. So you want to be able to have a pretty decent test kit that will not only measure cyanuric acid levels, but will also be able to measure appropriate chlorine levels. Okay. So we've talked about the six forms of chlorine. What's a what's a good number as far as what you need to maintain in um in um in your pool? Well, generally speaking, the ideal range for free chlorine, which is the active form of chlorine that's actually sanitizing and oxidizing, is about two to four parts per million. A minimum of one, uh, ideal of uh no greater than ten. Most health departments in the country say, okay, ten parts per million, that's enough in the water. Even though you can still have more. Uh people tend to freak out when they see these, you see high numbers, things like that. Now, for spas, uh the ideal range is three to five parts per million because there's hot water involved with it. And the whole hot water chemistry thing is is a whole nother podcast down the road. So two to four parts per million is is what you're is with what you're reading. Now, how do you how do you test for it? Well, uh, for free chlorine, you have to use a DPD test kit. And DPD is a pink color that you compare it to a chart of some kind, or maybe you do a drop test with it and count the number of drops it takes to go from pink to colorless. Uh, test strips will have uh certain ranges on them. But the concept here is testing, um, and testing on a on a fairly frequent basis. And um, as a service person, your that that that's part probably part of your contract is to test the water weekly or every other week or what whatever your contract calls for. But you should also be able to instruct your your customers on how to test for chlorine levels in between, okay, between visits by you, the expert. Okay, and again, a variety of different ways that they can do that, and that's available today. So that's my chlorine talk for today, okay? Um, in in a big, big nutshell. Um uh we're gonna be talking about um bromine down the road, other forms of chlorine, things like that. Oh, okay, here's wait a minute. Before I leave you, let me let me touch base on the thing. Uh it's not a form of chlorine so much as it is chlorine that's being added to pool and spa water. And that's uh salt water generators, uh SWGs, chlorine generators, whatever you want to talk uh call them. Been around for a long, long, long, long time. But only I'd say within the last 30 years or so has the popularity of the and the efficiency and the cost uh kind of lowered and efficiency has increased, and they're available now for uh commercial properties and not just uh uh private residences. But what the system does is in a nutshell is that you take water, which is H2O, and you add salt to it, which is NaCl. NaCl plus H2O kind of combines and plays with itself, and one of the things that pops out is something called HOCL, hypochlorous acid, which is the um form of chlorine, a free chlorine that is the active sanitizer and oxidizer. So you're producing chlorine. A very efficient way to produce chlorine. Um long-term costs are low. Initial costs might be a little bit high because of the actual system itself. But uh down the road, remember it is you're you're you're using salt. Salt, this is what we put on french fries, you know, how we season our food sometimes. Um what they tell you not to have when you're have high blood pressure. But still, um it it's a it's a way to produce chlorine, and it's not a form of chlorine necessarily, but it's still worth recognition and and discussion, brief discussion here about it. Um I personally like uh salt water systems, chlorators. I think it's it's a lot of common sense is involved with that. Um it's it's efficient, it's simple to use, um, easy to test for, that kind of thing. Um the only disadvantage sometimes to pouring generators is that they tend to push pH up. Um so you have to be careful, you have to keep an eye on your pH. And that's appropriately to bring it down if you need to. So that that's what we've got today, folks. We talked about chlorine, probably for 99% of what what I talked about already. However, uh a couple things to to to talk to you about before I leave you for today. Um, if you have any ideas on topics or any technical questions, please feel free to contact us at talkingpools at gmail.com. Talkingpools at gmail.com. And um send in your your question or or your recommendation for a topic. And if we use that particular idea for for whatever reason, we're gonna send you something. We're gonna send you a what the fuck app. Um skillfully designed by by Ruiz Nakovitz, uh, proudly worn by those of us who don't have hair a lot. Um, but we'll send one out to you. So uh drop us a line, let us know you're out there. Um again, this is Talking Fools. Um this is uh the pre-eminent uh podcast to talk to people who actually work with their hands in our industry. And we hope you pass along enough information, some good information to everybody. So take care, everyone. Uh have a great rest of the year, but I will be talking at you every Thursday. Take care. Bye-bye.