When Your Saltwater Pool Takes a Winter Nap

Cold water doesn’t just chill your pool—it changes how your salt system works. We break down what really happens when temperatures drop, why most cells throttle or shut off around 50 to 60 degrees, and how to keep water clear without burning through gear or cash. If you’ve ever wondered whether to pull the cell, which sanitizer to lean on, or how to set yourself up for an easy spring, this walkthrough gives you a step-by-step plan.

We start with freeze protection and the simple move that prevents expensive damage: remove the cell and install a dummy cell when hard freezes or power outages are possible. From there, we map out a winter sanitizing strategy built around trichlor tablets in a floater—not the skimmer—to deliver slow, steady chlorine while topping up cyanuric acid. You’ll hear practical tablet dosing for 15,000 to 20,000 gallon pools, why cold water slows dissolution, and how a modest tablet plan can place your CYA near the 70 to 80 ppm sweet spot for salt systems once the sun returns.

When storms zero out your chlorine, we explain why liquid chlorine is the best fast-acting boost for salt pools in winter. Its byproduct is sodium, so you avoid adding calcium that can scale up your cell plates. 

• freeze risk to salt cells and dummy cell use
• why cold water reduces electrolysis and output
• heated pool exception to winter shutdown
• trichlor tablets as winter sanitizer backbone
• avoid skimmer placement and use a floater
• tablet dosing by pool size in cold water
• winter CYA top-up strategy to target 80 ppm
• liquid chlorine boosts without calcium byproduct
• verify salinity with a digital meter in spring
• switch off tablets and reactivate the generator

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Chapters

• 0:00 Welcome And Winter Focus
• 2:33 Freeze Risks And Dummy Cells
• 3:49 Why Cold Water Shuts Cells Down
• 6:31 Heated Pools And Production
• 7:33 Switching To Tablets In Winter
• 9:00 Safe Tablet Use And Floaters
• 10:20 Cyanuric Acid Strategy
• 13:25 Tablet Dosage By Pool Size
• 15:35 Liquid Chlorine For Boosts
• 17:47 Spring Startup And Salt Testing

Transcript

SPEAKER_00: 1:02

Hey, welcome to the Pool Guy Podcast Show. In this episode, I'm going to talk to you about the winter months when the pool water is getting colder and your saltwater system. There are some notable things to know about a salt water system in the colder winter months, especially when you leave the pools open all year round, or those areas where you leave the pools open all year round, I should say. 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. I'll caution you that if you are in these areas where you can get freezing temperatures and you do leave the pool open, there's parts of Texas, there's been deep freezes that have hit areas where the power has gone out and it's been you know freezing temperatures. And one thing that you would want to do to prevent damage of the salt cell during the winter time is to remove the salt cell and put a dummy cell in its place. They do sell various dummy cells for the pent there and hayward systems. You can purchase those. If it does freeze, what happens is that the water will expand inside there and it'll crack the salt cell and pretty much destroy it and ruin it. So if you see pictures of a deep freeze in Texas from a few years ago, you'll see a lot of salt cells that exploded basically from freezing, the water freezing, crystallizing, and then expanding when it defrosted and cracking the plastic. They're usually pretty robust, but under those circumstances, the salt cell is not going to work. And of course, if you close your pool down in the wintertime, you want to remove your salt cell. That's part of the closing procedure. But in those areas like California, Nevada, Arizona, Florida, parts of Texas where you don't close your pool, leave them open all year round, there is something to note about the salt system is that it uses electrolysis to turn the salt, sodium chloride into chlorine, and as the water temperature drops, it slows down dramatically. Electricity does not conduct really well in cold water, and so you're gonna see a significant drop-off of production. Even the cells will shut down, a lot of them will have a cold light indicator or cold water or display water temperature too low, and usually around 50 or 60 degrees is when the salt cells will shut down because of the cold water, and it's just not able to really do its process to keep it simple in cold water. Now, there are some good things about the cold water, of course, is that you know algae and bacteria grow slower in cold water very slowly. In fact, it may not it may seem like algae doesn't grow in cold water at all, but it is growing slowly in some cases. So it's one of those things where it's not a deal breaker, I should say, to have a salt water system because in the cold months it shuts down. In fact, no one's using the pool in the cold months, so it's actually better that it shuts down and you're kind of saving the life of the salt cell by not using it, you know, 365 days out of the year. Now, of course, if you heat your pool in the winter to 70 or 80 degrees, well, I guess you would probably heat it to 80 degrees in the winter. 70 is probably still cold for most people. Now I had a customer that he was, you know, one of these workout buffs, and he really liked staying in shape, and he would heat his pool in the wintertime to about 85 degrees, and his gas bill he said was about twelve or fourteen hundred dollars a month, and he didn't care. He was like, I'm just gonna use my pool all year round. So in that situation, of course, the salt system is not gonna shut down because the water temperature is being artificially elevated by the heater, and it's just basically like summertime for the salt system, it won't know the difference. But in cold water, there is a big marked difference. Most systems will know that the water temperature is cold. There's a there's a temp sensor in there for the water temperature, and if it gets below a certain temperature, it'll shut the system down, or you'll it'll produce very low, very low amount of chlorine because of the fact that it just can't produce in the winter time. So you have to switch over to a different sanitizer in the winter time. In my opinion, the best chlorine type to use in the wintertime in a salt water pool are trichlor tablets. And I'll give you a few reasons why I primarily use trichlor tablets and salt pools in the wintertime. So you'll have to have a floater because most pools with a salt system, some of them have a chlorinator built in and some don't, but most of them will not have an inline chlorinator, so you'll have to get a floater. This is very important that you don't just put the tablets in their skimmer. Now, there's a lot of reasons why you don't want to put tablets in the skimmer, but briefly I'll just say that trichlor tablets are very acidic, they have a pH of about 2, 2.7. And if you put them in the skimmer basket, if you're running in the pool 24 hours a day, just really no worry about it because the water is flowing through. But if when you turn the pool off, all the acidic water sits in the skimmer, and then for 10 hours or 12 hours and the pool's off, it's just sitting and building up. You turn on the system, and all that acidic water goes right through the system, and that could cause staining out of the return line, staining in the main drain of the pool, and it could damage the equipment. So you definitely want to have a floater for the trichlor tablet in the winter time. Here's why I suggest trichlor tablets in the winter because half of the makeup or half of the ingredients of the trichlor tablets is cyaneric acid, and for the summertime you want to keep your salt water pool cyaneric acid at about 80 parts per million. And the way to do this, of course, is to add cyaneric acid to the pool directly either using liquid pool conditioner or the granular or the powdered cyaneric acid, and you'd have to buy the product and add it because the salt system does not have any stabilizer built in. There's no cyaneric acid being produced by the salt water system, and the only way to add it is manually at the beginning of the season. And as the pool, of course, evaporates, the water evaporates, and you get some rain in your area, the cyaneric acid level drops down with nothing replenishing it because the trichlor tablets, like I mentioned, are about half by weight cyaneric acid. So if you're using trichlor, you're adding cyaneric acid to the pool. But if you're not using trichlor tablets and you have a salt water system, you're not adding any cyanaric acid. I think you're following me here. So in winter time, since the pool water is pretty cold anyway, the tablets are going to dissolve very slowly in the floater. But as they dissolve in the wintertime, and you don't need too many tablets, I should emphasize this. If you have, I'm just gonna give you some kind of ballpark sizes of pools and how many tablets I usually use in the wintertime. If you have a 20,000 gallon pool, one tablet in the floater, pretty much closed off all the way, is sufficient in you know 50 or 60 degree water temperature to sanitize that pool. If you have a 15,000 gallon pool, I would break that tablet in half in some cases and put it in there. You could put a whole tablet in, it's not gonna cause a problem, in my opinion. So one tablet per 15 to 20,000 gallon pool is sufficient. Smaller pools, you may want to break the tablets in half and you know, use half a tablet in there because there's really not a big chlorine demand in cold water. The nice thing about the trichlor tablets, then you if you're using, you know, maybe one tablet every two or three weeks in the pool, maybe one tablet a month in some cases, depending on how cold the water is or how small the pool is, you're adding cyaneric acid to the pool, but you're adding very small amounts of cyaneric acid. So here from November through about April, beginning of April, when the water starts heating up enough to where the salt system reactivates, you may use five or six tablets, let's say basically. I'm gonna just say you're gonna use, I'll just keep it simple and say you're gonna use ten tablets. How's that? That way we can do the math much easier. Let's say again, 10 tablets, eight ounces per tablet. In the wintertime, that's about 80 ounces of total chlorine tablets. About half of that is cyaneric acid, maybe 48% to be more accurate. So if you're using 10 8 ounce trichlor tablets, you're adding about 2.4 pounds of cyaneric acid to the pool in a winter time. That's a kind of a boost for your pool in the summer, so that when you go to add the cyaneric acid or conditioner or stabilizer to the pool, however you want to phrase it, you already have some that you're adding to the pool in the wintertime. Even if you double that, you're using 20 tablets in the winter time, that's going to add about five pounds of cyaneric acid to the pool. And that might just be enough cyaneric acid for the whole season for your salt water generator, depending on your pool size. You have to kind of do the math and the calculator based on your pool size. So you're not adding a ton of cyaneric acid in the wintertime to the pool, and you're kind of recharging the cyaneric acid that you lose during the regular course of the season for the salt water generator, if that makes sense. So that's the benefit of the trichlor tablets, of course, is that you're adding some cyaneric acid in the wintertime, which will come in handy and beneficial in the summertime. Because a saltwater pool does need cyaneric acid in there to protect it from being destroyed by the sun's UV rays. Now, when they first came out, I'll just go back and share this story. When the salt water systems first came out, I was doing pool service, of course, when they first hit the market. Penthare was one that started making a lot of them with the IC IC systems and tetochlore systems. And the Penta rep was like, yeah, this is great. This is a great way to sanitize the pool. And you don't need to add cyaneric acid to it because it's going to be producing chlorine all the time for you. And it's something great. That was one of their sales pitches. And it turns out you do need cyaneric acid because, as Bob Lowry says, one reason why you need it is because all that chlorine comes out of the return jets. Maybe you have two return jets in the pool, and it's a highly concentrated amount of chlorine coming out of there, and the sun's UV rays will destroy most of that in that concentrated area, unless you're protecting it with the cyaneric acid. Now, the old school of 30 to 50 parts a million does work effectively in pools that are using you know liquid chlorine or calhypo. But in a real world situation, since there's so much chlorine coming out of the return jets in such a concentrated area, you need a higher level of cyaneric acid to protect it, and that's why 80 parts a million has kind of become the industry standard as far as the cyaneric acid level in a saltwater pool. So the tablets will help you achieve that in the wintertime, and you may not have to add any cyanaric acid products to cyaneric acid razors or products, you know, stabilizers or powder or liquid stabilizer to the pool at that point in the winter time. Now, one other chlorine type that you can use in the wintertime, let's say you're using tablets and you have a pretty major rainstorm and the chlorine level zeroes out in the pool, which does happen because the trichlor tablets in the winter time, I did mention that they dissolve very slowly in the floater. They're not going to give you a large dose of chlorine because of the cold water and the fact that they don't dissolve rapidly in the cold water. So there are occasions where the chlorine level is going to drop down because of a rainstorm, or maybe you didn't put enough trichlor tablets in there and they were dissolving too slowly. So let's say you check the chlorine level and it's at one part per million. Well, the best chlorine type to use to raise the chlorine in the pool, in my opinion, would be liquid chlorine. Why liquid chlorine over calhypo? Because liquid chlorine has a byproduct. They all have byproducts. Trichlor has cyanuric acid, calhypo has calcium. Well, the byproduct of liquid chlorine is sodium. So you're adding some salt to the pool. Now, as you know, in the winter time, you know, you get some dilution, and then in the summertime you have to add bags of salt to the pool to bring up the salt level in the pool. Well, if you're using liquid chlorine as another sanitizer in the winter, along with trichlor tablets, you're adding cyanuric acid with the trichlor, and then you're adding some sodium to the pool, not a huge amount, but you're adding some sodium to the water, and that is the most compatible chlorine type to salt for a salt water generator. Because if you're adding calcium to the pool, you may cause the salt plates to get some calcium buildup with calhypo. So adding liquid chlorine is kind of like a a substitute to the salt water system that's very, very similar, and the byproduct again is sodium. So liquid chlorine is a great way to raise the chlorine level in the pool in the wintertime with a saltwater system when you need to. If the trichlor tablets are not sufficient to raise the chlorine level up and keep and maintain the chlorine level, I should say, month in, week in and week out while you're not using the salt water generator. Now, coming out of winter, here April and May is when we start firing up the salt water systems again. And one mistake that is often made is to trust the salinity reading on the system itself. Now the water is still fairly cold. The cell might even be dirty from you know if you didn't take it out and put a dummy cell in. And so I wouldn't trust the salinity reading of the system. Hayward is notorious for this, giving you really low salt readings when it's really not low. Some Pentair systems will do this as well. So I would say when you're starting up the system again in April or May here in California, get a digital salinity meter, buy one on Amazon. You know, I like the Hawk brand, I like the Lamotte brand ones. These are great salt water salinity testers. Get one of these and test the salinity level. A lot of these will compensate for temperature, and then you're going to get a true salinity reading. You don't want to overdose the pool with salt at the beginning of the season because then you're going to drain some water out, or you may have too much salt when the system really fires up and is running at you know with the water temperature at the correct level. So make sure you check the salinity level with an independent digital salinity salt reader, and then you can add salt accordingly once you get the accurate reading. And again, everywhere it's different when the system comebacks come back, when the salt systems come back online, I should say. And here in California, April and May are the months when the water temperature gets into the 70s, and the salt water systems are able to reactivate and make chlorine for the pool. But then you just take out the floater, stop using the trichlor tablets, and then the salt system will generate the chlorine during those spring and summer months for you and into the fall. And into the winter months here again, from usually late October into the beginning of March, you're using an alternate chlorine type because the salt water generators are just not producing chlorine during that time. If you're looking for other podcasts, you can find those on my website, swingingpointlearning.com. Click on the podcast icon. That'll take you to a drop down menu of over 1800 podcasts. And if you're interested in the coaching program that I offer, you can learn more at PoogaiCoaching.com. Thanks for listening to this podcast. Have you guys your week and God bless.