The Truth About Liquid Pool Chlorine

Sunlight, strength, and shelf life decide whether your chlorine dollars deliver crystal water or fade by Friday. We unpack the real-world playbook for using liquid chlorine (sodium hypochlorite) as a primary sanitizer—what it is, how strong it should be, and why pairing it with the right stabilizer keeps free chlorine steady all week.

We start by clarifying the difference between commercial-grade liquid chlorine at 10 to 12.5 percent and household bleach at 5 to 8.25 percent. Then we get practical: how regional supply chains affect price and potency, why UV burns through unstabilized chlorine without 30 to 80 ppm of cyanuric acid, and how much FC you can expect to lose per day under ideal conditions. If you’ve ever shocked to 10 ppm and returned to a near-empty pool a week later, this explains it.

From there, we map clean strategies for pros and homeowners. Learn the advantages of using fresh liquid chlorine for fast, residue-free shock and algae control, plus where cal hypo and dichlor fit—and how their byproducts (calcium and stabilizer) change water balance over time. We show why sodium is the least disruptive contributor to TDS and how to handle saltwater pools when the cell is down. You’ll get clear storage guidelines to protect strength, buying tips to avoid old stock, and a simple hybrid plan: dose with liquid for control and use a few trichlor tablets to bridge the days between visits without spiking CYA.

• what sodium hypochlorite is and how it compares to bleach
• commercial strength vs household strength and why potency matters
• regional pricing, availability, and distribution effects
• unstabilized chlorine behavior and required CYA range
• weekly service limits and why chlorine fades between visits
• supplementing with trichlor tablets or a liquid feeder
• pros and cons vs cal hypo and dichlor byproducts
• shelf-life loss, storage best practice, and buying fresh
• algae control, shock tactics, and quick cleanup use cases
• the trichlor plus liquid approach to control CYA

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Chapters

• 1:53 What Liquid Chlorine Really Is
• 3:33 Strength And Cost By Region
• 5:32 Unstabilized Chlorine And CYA Needs
• 7:14 Weekly Service Limits And Dosing
• 9:49 Old School Vs Modern Supplementing
• 11:09 Best Uses And Byproducts
• 13:31 Shelf Life, Freshness, And Supply Chains
• 15:45 Value, Side Effects, And Practical Drawbacks
• 17:59 Algae Control And Shock Strategy
• 19:19 The Trichlor + Liquid Combo

Transcript

SPEAKER_00: 1:03

Hey, welcome to the Pool My Podcast Show. I recently did a podcast on Calhypo, and I thought I would follow up with one strictly on liquid chlorine or sodium hypochlorite, and I'm going to go over the pros and cons of using liquid chlorine out on your pool route, or if you're a homeowner, using it as your primary sanitizer in your backyard pool. Are you a pool service pro looking to take your business to the next level? Join the pool guy coaching program. Get expert advice, business tips, exclusive content, and get direct support. From me, I'm a 35-year veteran in the industry. Whether you're starting out or scaling up, I've got the tools to help you succeed. Learn more at swimmingpoollearning.com. Liquid chlorine or sodium hyperchlorite, and this is well known as bleach as well, and it's interchangeable. When you talk about liquid chlorine, a lot of people don't really realize that it's the same as household bleach. Of course, unscented, and it's one of those things where it's basically the percentage that will signify if it's liquid chlorine for pool service use or household bleach for laundry use. I'll just explain that right here. That most of the pool service grade liquid chlorine is 10% or 12.5%, which is what Hasa uses in their liquid returnable. So 12.5% is pretty much the industry standard for liquid chlorine. It's the strongest concentration in a one-gallon container or a two and a half gallon container of chlorine. And it's what we would use, we'd consider commercial strength if you wanted to classify it, compare it to bleach. Bleach is anywhere from 5% to 8.25%. So if you're using a gallon of household bleach, you'd have to use two of them, sometimes or more, but roughly two gallons of household bleach to equal one gallon of the 12.5% commercial grade liquid chlorine. So that's kind of a visual of the strength of the commercial grade liquid chlorine that we use versus the household bleach. Now, of course, the price of liquid chlorine varies by region. Florida is still going to be probably your least expensive area to get liquid chlorine, where California and Texas, I think, are on the high side as far as liquid chlorine. And in some areas you can't even get liquid chlorine, like on the Hawaiian Islands, you probably can't get that. So there are some reasons for this, and the production of liquid chlorine, of course, takes a factory basically to make the product. So you have to have the location for the distribution of it, because it does have a shorter shelf life, which I'll touch on a little later when I talk about the shelf life of the product. But just note that the strength of liquid chlorine, it's an important factor. If you go to Home Depot and you buy the liquid chlorine there, it's not going to be, and at least in my area, it's not the commercial strength of 12.5%. That would have to come from your wholesale supplier or from a pool store to get the Hasa Returnables in my area. They're the main supplier of liquid chlorine on the West Coast, and that is where you would get that strength from the 12.5%. And believe me, it is really important to get the right strength of liquid chlorine, otherwise, you're wasting your money buying a weaker chemical, and it's not really cost effective unless you're using the commercial grade liquid chlorine, in my opinion. Liquid chlorine is also considered an unstabilized chlorine. What this means is that there is no cyaneric acid built into the product, and so there is nothing that's going to protect it from the sudden UV rays, and that's why the pool has to have a cyaneric acid level or conditioner level or a CYA level of a certain percentage for it to be effective. I shouldn't say percentage, I should say more or less a level of cyaneric acid. So we would require cyaneric acid at at least 30 parts per million to about 80 parts per million for liquid chlorine to be protected in the pool when you pour it in there from the sun's UV rays. And it differs by region, and it's one of those things where if you're using unstabilized chlorine like cal hypo and liquid chlorine, you have to realize that there's really it's really hard to maintain a pool strictly with liquid chlorine if you service it once a week, unless there's a chlorine chlorine feeder there at the stop, or if you're using a combination of trichloride tablets and liquid chlorine, that's perfectly fine. Liquid chlorine is not something that you could put in a gallon of it at the beginning of the week. And at the following week, when you get back there, let's say you service the pool on a Tuesday, you pour in a liquid of a gallon chlor a gallon of liquid chlorine on Tuesday, and of course you raise the chlorine up to say 10 parts per million. But by the time you get back there on that following Tuesday, more than likely that chlorine level will be close to two parts per million or maybe less, because the chlorine really isn't the liquid chlorine is not made as something that's going to stay in the pool all week long without redosing of the liquid chlorine if that makes sense. Whereas trichlor tablets dissolve slowly in the pool, calhypol tablets will dissolve slowly in the pool as well. There's nothing after you pour liquid chlorine in the pool that keeps it in the pool long term, and it eventually will be used up from bather loads or anything in the pool that would use up the chlorine along with time and the UV rays hitting the pool. So this is something to be aware of. That liquid chlorine, in my opinion, is a great supplemental chemical to go along with some stabilized chlorine that you have in the pool during the week, or if you have a roller chem or a liquid feeder, that's the best way to put liquid chlorine in the pool. And if you do commercial pools, you're gonna be back there, of course, three or four times a week. So using liquid chlorine is perfectly acceptable because you're gonna be there to redose the pool. You just couldn't do that in a residential backyard unless you're a homeowner using liquid chlorine, then of course you can dose your pool every couple of days without really worrying about it. But for pool service, liquid chlorine and calhypo are unstabilized, so they're not gonna stay in the pool all week long. And according to Bob Lauer, you're gonna lose about one part per million per day under ideal conditions. Other conditions will accelerate it, microalgae, higher bather loads. But if no one's using the pool and there's no algae present, you can figure that you're gonna lose one part per million per day, and so you're going to need to redose that pool at some time. Back in the old days, we used to leave a case of liquid chlorine with our customers and tell them, you know, if we were there on a Tuesday, we tell them pour a gallon in on Friday, and they would put a gallon in. But that's the old school way of doing it. Customers were more involved. There wasn't really much technology out there, there wasn't really any liquid feeders. There were some rudimentary feeders, I should say, back there for commercial applications, but nothing for residential. So the customer had to pour in a gallon of liquid chlorine sometime during the week, so the pool would last to the following week. And it wasn't really a big deal, it's just that the customer has to be involved in it. Pouring a gallon of liquid chlorine, you have splashing, and it's one of those things where you really don't want the customer to do that on a regular basis nowadays. And so using a combination of liquid chlorine and maybe trichlor tablets or halchipo tablets during the week is a great way to supplement the liquid chlorine you're using in the pool. I would say that liquid chlorine, of course, is the best chemical to use in the pool when you're bringing up the chlorine level in the pool. I wouldn't recommend using dichlor, for example, because you're adding cyaneric acid to the water with dichlor. Although dichlor does serve a purpose, and you know, I like using dichlor when I'm starting a new pool, and I need to bring the chlorine level up and add cyaneric acid to the pool at the same time. Calhypo fits a similar category to liquid chlorine, but liquid chlorine I think is much faster acting, and it has a side effect or a byproduct that affects the pool less than cal hypo, which adds calcium to the water. Liquid chlorine, of course, will add sodium to the water or salt, since it's called sodium hypochlorite as this as this parent name of the chemical, and it's going to be adding salt as a byproduct to the pool, which in my estimation of the total dissolved solids or TDS of the pool, salt is an element that has the least effect on the pool itself. And so I would add salt all day long over calcium or cyanaric acid from dichlor or trichlor. And if you have a salt water pool on your route where the salt cell isn't working, non-functioning, the customer is not replacing it, and you check the salt or salinity level of the pool, and you're at 30, let's say 3,200 parts per million, but the salt generator is not operating. You know that in most cases you can maintain that pool perfectly fine with liquid chlorine and trichlor tablets, and the salt in the water doesn't really have a detrimental effect on the water quality or your ability to maintain that pool. So that's why I'm saying that salt is probably the least impactful part of the total dissolved solids, in my opinion. So using liquid chlorine, you're adding a byproduct, yes, but it's not a byproduct that's doing a lot to the pool water, and plus you can do partial drains to lower down the TDS of the pool very easily using liquid chlorine. Now there is something to be said about the shelf life of liquid chlorine, and this is something why I mentioned why they can't really send it over to Hawaii or it's not that popular there because of the fact that it does have a lower timetable than say Calhypo, which probably has a good two-year shelf life, maybe even more. I was at a pool one time and I found this these old bags of Calhypo, they they must have been five or six years older, maybe even older, because I couldn't read the labels too well because they were already fading from the chemical in the bag, kind of eating through, and they were just big solid bricks at that point. The the granulars had solidified into these bricks, and so I just as a you know just trying in the pool, I I figured I would use it. So I dropped one in the pool and I tested the chlorine level, and sure enough, it still showed a pretty good chlorine level, and I would say they're they were at least five to ten years old, the bag of calhypol that I put in there. But liquid chlorine does not have that kind of shelf life, and it's one of those things where you're gonna probably lose about one percent of the strength per month, and so if you have 12.5% liquid chlorine and you have it in your backyard for over a month, you're probably gonna get down to about 11.5%, and then after two months, you're at 10.5%, and then you can degrade that all the way down. I don't know if there's like a certain half-life of liquid chlorine, but you can it does degrade over time, and you want to store it in a cool, dry place. And this is why it's not something that you could buy, you know, a pallet of liquid chlorine and leave it in your backyard because the strength does deteriorate over time, basically, and so you want to make sure you use liquid chlorine when it's fresh, and that's why the hostage returnables are great because they bring them into the distributor right from the factory, and this is exactly why you can't have liquid chlorine in an area where you don't have the distribution or the production available because of the shorter shelf life. If you go to Home Depot and buy some liquid chlorine off the shelf, it may have been sitting back there for six months. You don't know. I'm sure there's a date on the box somewhere, so you have to make sure you buy the professional grey liquid chlorine from a reputable supplier. Like in Florida, I know there's like six chlorine factories down there of different brands, and that's why the chlorine is really inexpensive, and they sell it by the two and a half gallon jugs, which is kind of a weird thing for us California Pool Pros, because we just get the gallon of returnables, and the two and a half gallon jugs are kind of foreign to us, but the price of liquid chlorine in Florida, of course, is much lower than everywhere else in the nation because they have so many factories producing it and it's easily available, and the strength is of course strong and kept up because of the close proximity to the to the distribution of liquid chlorine. And the same thing with Hasa, the reason why they haven't expanded past Texas is because you really need that distribution chain to keep that liquid chlorine fresh and viable for the pool pro. And this is something to consider when you're buying liquid chlorine, you want to buy it from a pool store that has fresh stock that's rotated so that you have the full potency of the chemical. Now, as far as strength, I think liquid chlorine, if you do it, it's hard to kind of do this because you're using a liquid measurement of a chemical versus a powder form of chemical. But if you listen to the Calhypo podcast, you know that liquid chlorine is stronger by content in the gallon form than cal hypo, a pound of cal hypo. So dollar for dollar, liquid chlorine is the stronger shock, it's fast acting, like I mentioned. You can pour it directly in the pool. It doesn't really have any real side effect except it raises the pH slightly for a little bit of time. But there's been a lot of studies saying that the pH will actually go back down to the normal level pretty rapidly, and you're adding sodium as a byproduct to the pool. So there really isn't too many cons about liquid chlorine except the fact that the shelf life is shorter than say calhypo or dichlor, if you're using those as your sanitizers along with a trichlor supplement in the pool because the trichlor has a stabilizer, and then liquid chlorine and calhypo do not have any stabilizer in them. So, to quickly recap, if you're using liquid chlorine, you're going to put about eight parts per million, eight parts per million of salt per one part million of chlorine added to the pool, and this of course will increase your TDS level in the pool. There's no chlorine product without a byproduct, so just keep that in mind. The negative is storage, of course, it degrades over time, and the gallon of liquid chlorine can be a little heavy at 10 pounds roughly per gallon. So that's something to consider as well, and it's something that's not a big drawback, but it is a factor. It takes up a lot of room in the back of your truck as well. That's a factor as well, versus a powder type chlorine. But all in all, liquid chlorine, of course, is fast, fast-acting, extremely strong and potent, and is something that is an industry standard. A lot of pool pros like liquid chlorine when they shock a pool over Calhypo for a number of factors that I mentioned here. And Calhypo, of course, is still very popular. And I would say that they're interchangeable chemicals to a point where liquid chlorine has a less effect on pool surface types. You could use it in a vinyl pool than a fiberglass pool without worrying about staining it. There's no chance of oxidizing the pool surface and causing a black stain. And it's great to kill algae, it's highly effective in killing algae. In fact, if you go to the trouble-free pool form, you'll see that they're not big on algacides or any kind of mineral technology. They promote borates and liquid chlorine because bleach, as you know, kills germs and bacteria. And if you have bleach in the pool, it's going to have the same effect. So it's great at killing algae, it's great at breaking combined chlorine, it's a great shock for a pool, it's great for green pool cleanups. There are so many great benefits of liquid chlorine that I have no problem promoting it and saying that it should be your primary sanitizer as far as shocking and adding the chlorine and bringing the chlorine level up. And if you do have a chlorine feeder, liquid chlorine feeder, it's great, of course. But if you don't, using it in conjunction with trichlor tablets is an excellent combination. The trichlor tablets are adding cyanaric acid to the water, and the liquid chlorine is not. So it's a great way to do the combo approach where you're using liquid chlorine as your primary sanitizer every week, but you're using some trichlor tablets to kind of let a small amount of chlorine out into the pool during that week. And to me, it's a great combination because the byproduct is sodium and it's not adding anything like calcium or cyaneric acid to the water, and it's a great way to use trichlor tablets safely and minimize the cyaneric acid rise in the pool by using trichlor. If you just use trichlor tablets exclusively in the pool, the cyaneric acid level is going to rise rapidly to a level that's pretty much unsustainable for pool care. Whereas if you have liquid chlorine and you're supplementing the trichlor tablets with it, it's to me a perfect combination and a perfect use for liquid chlorine in a pool. And if you're looking for other podcasts, of course, you can find those on my website, swimmingprolearning.com, on the podcast icon. Click on that, and there'll be a drop-down menu of over 1800 podcasts for you there. And if you're interested in the coaching program that I offer, you can learn more at poolguidecoaching.com. Thanks for listening to this podcast. Have the rest of your week and God bless.