Bob Lowry Explains: Cold Weather Pool Care Made Simple

Cold water changes everything. As temperatures slide, algae take a back seat, chlorine demand dips, and the Langelier Saturation Index tilts toward corrosive—quiet shifts that can quietly chew through plaster and equipment if you are not paying attention. We sit down with industry legend Bob Lowry to map a simple, reliable winter playbook that protects the vessel, extends gear life, and saves money when demand is low.

We start with the biology: algae reproduction slows around 55°F, which means you can safely run lower free chlorine. But that win comes with a catch—temperature drags LSI downward, so water gets hungrier for calcium. Bob explains how a small bump to pH and total alkalinity can stabilize balance without chasing numbers, and why calcium hardness targets still matter even in the off-season. We talk through the practical side, from long gauntlet gloves that make cold work bearable to smarter run-time choices. If you are tempted to run the pump two hours “just because,” hear why that middle ground is worse than a proper turnover.

Cyanuric acid gets special attention. After a summer of tabs, winter is the perfect time to lower CYA with a partial drain and refill. Bob also shares why CYA may drift down on its own—and in rare cases crash—due to specific bacteria when chlorine is low. The takeaway is simple: even in winter, test with intent, keep CYA in the 30–50 ppm sweet spot, and nudge LSI back to balanced as temperatures fall.

• Cold water reduces chlorine demand and slows algae growth
• LSI drops with temperature, raising corrosion risk
• Open vs closed pool choices by climate and power reliability
• Salt generators underperform below about 60°F
• Effective winter circulation strategies and freeze protect
• Partial drain to reduce high CYA from summer tabs
• Rare bacteria can consume cyanuric acid in low-chlorine pools
• Preventing stains, rings, and surface damage during dormancy
• Practical tweaks: raise alkalinity with bicarb, monitor pH and calcium
• Cost control in winter with lower chemical usage

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Chapters

• 0:00 Welcome And Bob’s Health Update
• 3:38 Career Legacy And Teaching Foundations
• 5:19 Gloves, Cold Work Tips, And Setup
• 6:20 Cold Water Chemistry And Algae
• 7:51 Open Vs Closed Pools By Region
• 10:23 LSI Shifts As Temperature Falls
• 11:49 Salt Generators Below 60 Degrees
• 13:32 Winter Circulation And Freeze Protect
• 16:08 Texas Freeze Lessons And Risk
• 17:29 Managing High CYA In Winter
• 19:49 To Close Or Not In Border Climates
• 21:13 Stagnant Water Stains And Scale Rings
• 22:09 Practical Winter Balancing And Costs
• 22:41 Resources, Coaching, And Sign Off

Transcript

SPEAKER_00: 1:02

Hey, welcome to the Pool Guy Podcast Show. And this is Besta Bob Lowry. I'm gonna talk to Bob Lowry about the cold weather months and winter pool care. He'll give you tips and, of course, some strategies for taking care of those pools that are open all year round and for those pools that you close during the wintertime. 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 Swimming PoolLearning.com. You know, you've been living with this lung disease now for five years, over five years now.

SPEAKER_02: 1:46

Yeah. So you know, and and I feel fortunate anyway because when I was diagnosed with the disease and went to UCLA for the first time, they told me that that I had the statistics were that everybody lives somewhere between two and five years, and that you know, very few people live beyond uh five years with this disease. In a couple of weeks, it well, about ten days, it will be uh six years since the diagnosis. Amazing. Uh it is kind of I feel fortunate in to be here at all and and to be able to continue my my life's work and passion is is even better. So and maybe that's what keeps me going, you know. If I were sitting on the sofa, you know, waiting for the disease to overtake me, it probably would have. So even today, if I feel like I'm out of breath, I'll have to turn on my uh oxygen machine and supplement my breathing a little bit.

SPEAKER_00: 3:01

Let's tell the listeners a little bit about your history in the industry. I mean, you've you're pretty much a pillar of the industry. I I I only say this to a few people as far as being a pillar, and you've you've done so much with your literature and with your your teaching. You've been in the industry for over forty what is it, how many years now?

SPEAKER_02: 3:23

Uh this is forty-eight. It'll be forty forty-nine next year.

SPEAKER_00: 3:28

So it's it's pretty amazing the the legacy that you've created with your teachings and your your background. And I first found your your Ipsiv book um many, many years ago, and that was your first publication to them. That was I would say what twelve, fourteen years ago.

SPEAKER_02: 3:50

Oh, that was probably yeah, that was um 15 years ago, maybe. Um I think it's copyrighted in 2006, and it took me uh a year, a little over a year to write it.

SPEAKER_00: 4:07

So Yeah, that's that to me, that was a a big leap in knowledge. I mean, that was something the things that you wrote in that book 16 years ago are not dated. You know, there's some new discoveries, of course, but as far as the basic principles that you wrote back then, and so that's what you do is chemistry principles and they evolve and you've discovered new things. We talked about those in other podcasts. And today we're gonna, since you're wearing a jacket, we'll talk about cold weather and we'll talk about uh cold water and different things they have to be aware of. And just before I start, I'd like to let the the pros out there know that there's a pair of gloves that I wear in the winter time, and they're called Atlas Gloves, WG772M, and they're 26 inch long, so they go up to your your armpits, and they use them in butchers use them in the meat lockers, you know. And so these things are great for the pool water because and in your pool pool, you know, it kind of freezes to your hand when your hands are wet. So those gloves are just awesome out there in the cold weather. And I just put them on my dashboard and have the heater come on in between stops to warm them up again. And they get me through the winter months here in California, which is kind of wimpy because California probably isn't as cold as you know other states get out there. So as far as cold water, let's start with the first one. The chemical usage in a pool when the temperature is below 60, what happens with the amount of chemicals that the pool needs?

SPEAKER_02: 5:41

Well, the the needs are down just because things slow down with colder temperatures. The fact is that algae doesn't grow in I I've heard people say algae doesn't grow below 55 degrees. And for the most part, that's true. And for swimming pools, it's true. But there are algae not found in swimming pools that grow below 55 degrees. Garden variety algae that we get in swimming pools, it doesn't grow below 55 degrees. So when we get to 55, we don't need as much chlorine or as much uh disinfectant in the water because there's not an the algae isn't gonna uh reproduce. The cold water doesn't kill the algae, but it makes it so it doesn't produce or reproduce. You'll need less disinfectant, less algacides, and people say I'm gonna put a winter algacide in. I think that's a waste of money because if the water's gonna be 55 or less, you don't need an algacide.

SPEAKER_00: 6:52

Yeah, and in our area here, we don't close our pools down. I'm kind of skipping some of the questions here and moving them a little bit now that it makes more sense in this order. We don't close our pools here, we keep them open. So we're always adding muratic acid to keep the pH in balance and things like that still. What about those areas? And I know I've I get a lot of emails at the beginning of the season, people open their pools up and there's all kinds of different problems with staining, with you know, sometimes there's even algae in there if they open later in the season. Now, if we're here year-round balancing the chemicals, but in other states they just cover the pools, drain them down below the return lines. How does what's the difference? Why don't we do that? I mean, I know why we don't do it here because the pools don't get that cold. But is there a major difference between those areas like New York, you know, some parts of the Midwest where they winter wise their pools and California, Arizona, Nevada, Florida, Texas, where we don't do that?

SPEAKER_02: 7:51

If it were possible, they'd probably drain the water out of the pools in the north and and fill them back up when it when it got to be warmer, but they just want to keep the water in there. You know, they want to keep it from freezing and they need to protect the shell. And the best way, of course, to protect the the vessel is to have some water in it, even if it freezes. Um many times they they actually plug the lines and and put uh antifreeze in the lines and then remove the equipment and put it inside and then you know put the equipment back. So they're just dealing with a dealing with a a small body of water that doesn't have any any circulation other than what they you know stir up during the winter, and most of them are too lazy to go out when there's three feet of snow on the ground and go burst the pool or circulate things around. Who wants to do that? They sometimes uh drop a pump in there and pump the water around a little bit for a while, but for the most part, it's just a stagnant body of water for a few months until it warms up.

SPEAKER_00: 9:06

And that doesn't affect, I mean, does it affect the surface at all? I mean, I've probably never did any kind of saw any kind of studies about that versus areas.

SPEAKER_02: 9:15

It it doesn't really. Um of course, if the if the if the water is out of balance when you when you shut it down, there's a good chance that whichever way it's out of balance is going to have a problem before you open it back up.

SPEAKER_00: 9:32

I guess the main reason we don't do it in California, Nevada, Arizona, Florida is that the water temperature doesn't get cold enough to where it would interfere with the LSI.

SPEAKER_02: 9:43

Because I I know that in the LSI As the water temperature goes down, the the the water actually gets corrosive. Um and it affects the LSI. Um in general terms, it's about 15 degrees for each 0.1 on the saturation index. So if you're gonna lower the water temperature from, say, 80 degrees down to 50 or 90 down to 60, um, you need to account for the fact that it's gonna be 0.2 less. Sometimes that's a good thing, sometimes that's a bad thing, depending on where you started. But if you were slightly corrosive to begin with, you can be really corrosive uh uh if you if you don't raise pH or alkalinity back up, um, you're gonna have a problem with um the water being corrosive in that vessel. Um, it just slowly literally dissolves some of the vessel.

SPEAKER_00: 10:48

Yeah, so it's important to keep the water balance even in the winter when you have the pool open. I know a lot of people figure, hey, it's cold out there, I'm not gonna even bother with much, but that's not the case. What about a salt water generator? I know that most of the cells won't produce after a certain temperature, is that correct?

SPEAKER_02: 11:08

Right. Yeah, most of them, I think it's about 60 degrees, it might be 55. But once you get the water temperature that low, um you can't use electrolysis very well to make to make uh chlorine. So um they're pretty useless once you get below about 60 degrees, they're pretty pretty well useful.

SPEAKER_00: 11:30

You don't need all that chlorine anyway that it would produce in any way because as we said at the beginning, the chemical usage is really low. So it's really not a deal breaker if you were going with a salt generator.

SPEAKER_02: 11:43

Yeah, the the only thing that you may want to do is maybe even remove the chlorine generator if you can. Um depending on how it's it's uh plumbed, you may be able to take it out and store it someplace so that it just doesn't have water sitting in it for months on end with with no because I'm sure there's still uh a little leak of electricity in there anyway. You know, you there's it may be only a small amount, but there is a leak of electricity, and you know, you're gonna wear the cell out even more if you leave it plugged in.

SPEAKER_00: 12:19

So, what I do with mine is I have uh I have an extra cell that's no good, and I swap it out with the good one in the winter, and I turn my system off, and that way the good cell hopefully will last longer. I just started doing this because uh one of my cells burned out, died earlier than I expected. And I suspect it's because they left it in there all winter without removing it, uh, even if even if it was unproducing. And another thing that a lot of people will do in the winter is they'll tell the pool guy, well, since the water is cold, I don't need to circulate the pool much, so let's have it run two hours a day. Now, is there any logic behind something like that?

SPEAKER_02: 12:57

My bottom line advice is either don't run it at all or or run it for a turnover. But um don't don't just run it for a couple hours. That's that's probably worse than running it for for no time or for a turnover. So a couple hours probably probably is no good.

SPEAKER_00: 13:17

There's a lot of the pumps have the freeze protect mode where if the sensor cuts notices that the water is getting to where it's going to be freezing, it'll turn the pump on by itself. Right. And what's you know, we we kind of know the reason behind that because if the water freezes in the pipes and then it thaws out, it could crack him.

SPEAKER_02: 13:36

Yeah, and of course we had that in in Texas this past year, yeah. Where they had a freeze when nobody was expecting it, and and it ruined a lot of equipment and plumbing lines and and everything, because once the water freezes, it expands.

SPEAKER_00: 13:52

So that's in an area where they didn't really winterize their pools like here, because it doesn't it never really got to that point in most most of those areas that froze. I don't think the customers or the pool pros you know drained out the pumps and nobody anticipated that.

SPEAKER_02: 14:07

Yeah. And and even though they heard that the cold weather was coming, I think they didn't think it was gonna be that long. And and you know, because it's like when you put a a cube of of a tray of uh ice cubes in the in the freezer, you know, you put it in there and and it doesn't make ice five minutes after you put it in. You know, it makes ice four hours from now or whatever. So uh they I'm sure they were thinking, well, you know, it's just barely below freezing, and you know, it's only gonna be overnight, so you know, then nothing's gonna happen. But you know, once you get into days of it being that long, the water freezes everywhere.

SPEAKER_00: 14:51

Yeah. And I think the power loss didn't help either, because then the systems that had the freeze protect shut down. Right. Yeah. So it was kind of like a double double hit. And what do you think about draining the pool in the winter to lower the cyaneric acid level? Because a lot of people use tablets all summer. For me, I think in the wintertime it'd be ideal to drain the pool down partially to lower the cyaneric acid level in certain areas.

SPEAKER_02: 15:16

Well, you know, I'm an advocate of a lower cyaneric acid anyway, so anything that we can do to keep the cyanuric acid down around 30 to 50 ppm is is is a great idea. So um, you know, drain drain of you know some of the water out in the wintertime, and and when you fill it back up, the cyaneric acid will be less. Um cyanic acid does degrade um a little bit, just biodegradation, if you will. Uh it decomposes and uh it doesn't decompose very very quickly, but over the few months of winter you can probably drop it. Maybe about 5 ppm a month, it will drop just due to degradation. Um and also there with the chlorine level low, you may get some bacteria in the pool. And we have had pools that during the winter time have a significant loss of cyanuric acid. And for a while we didn't understand that, but um there is a certain type of bacteria that like to eat cyanuric acid. And and uh it's not too common, but sometimes it happens that it gets in the pool, and during the wintertime, since there's a low chlorine level, the cyan the cyaneric acid level drops down to zero because it's food for the the bacteria.

SPEAKER_00: 16:47

I wonder if that's the same bacteria they use in the bioactive hydrogen.

SPEAKER_02: 16:52

But the bioactive is uh is an engineered bacteria along with an enzyme. And the enzyme makes it go faster, uh the catalyst. And so the enzyme makes it go faster. But we've had pools where people say, you know, I opened my pool and my cyanuric acid level was zero. Um that's it it is possible, and it it is possible if uh the right bacteria gets in the pool.

SPEAKER_00: 17:23

Yeah, that's interesting. And so basically in the in the winter, when it gets cold, either you're in the area where you would winterize the pools, or you're in the area where you would just keep them open and try to keep the water balanced. And there's I mean, there's some areas that are kind of in between because I've gotten people that say they're in parts of Georgia, and some neighbors close their pools, others don't. And so there is that gray area in some areas where you can keep them open or you can close them.

SPEAKER_02: 17:50

Yeah, there are, and I don't know what parallel it might be north of, but you're you're right. You know, once you get kind of above the the the pool belt of the of the US, uh there's an area where you know you close it or you don't, you flip a coin.

SPEAKER_00: 18:11

And I guess the only harm of not closing it would be that freeze damage, you know, if you do get that freezing weather and you're not running the pump.

SPEAKER_02: 18:18

Yeah, you run that risk. You know, I I lived in North Georgia, which was where I lived, was up in the mountains and and it wasn't actually too far from Tennessee. Some people tried to run their pools year-round, and and just from year to year with the different weather, uh, one year it would be okay, the next year it wouldn't be. You know, so it was kind of a a hit or miss type of thing anyway in those areas.

SPEAKER_00: 18:44

Yeah, and I think for most of the the people that are in the sun belt, um California, Arizona, Nevada, Texas, Florida, once in a while we'll get a customer that says, Hey, you know, can I close my pool and cover it for the winter? And we try to explain to them that it doesn't get quite that cold to do something like that, that you know, for five months to have it covered. Can't really do that.

SPEAKER_02: 19:07

It's it's probably better to run it. Um, you know, water that sits for a long time like that, unless you are in a freezing condition, it just ends up causing problems. You you know yourself if you've got if you've seen a clear vessel that you've had water in and let it evaporate down to where you know you got uh a few inches off, it it it kind of stains the glass, or that stains the cup or whatever. And and and it's difficult to even wash it. It doesn't come off very well, you know, and it usually ends up using some vinegar or something trying to to get the glass clear again. Same thing happens in your pool. You know, you get you get that ring around the top, and as more and more water evaporates and the level gets lower, you get that ring. And and it may cause a permanent a permanent stain on some uh on some plaster pools.

SPEAKER_00: 20:06

Yeah, I guess another selling point would be the fact that the cold water can make it the water corrosive. And so as a pool tech you have to balance that water, even in the wintertime. So those those are all good and good points for the the pool pro when they run it if they run to a customer that that wants them to win a rise of pool in an area where it's not typically done.

SPEAKER_02: 20:27

And probably the easiest thing to do is just throw in some some bicarb and get the alkalinity up a little bit. You know, so it's it's probably better to do that.

SPEAKER_00: 20:38

And that's and that's in the areas like my area, a lot of the pool companies actually recover a lot of their chemical costs in the winter time because in the summertime, well, this year we're gonna talk about that in a minute, but this year the chemical cost is extremely high. So in the winter, when you're not adding a lot of chemicals to the customer's pool, you're kind of recruiting. If you're looking for other podcasts, you can find those by going to my website, swing for learning.com. On my website, I have a podcast icon at the top. Click on that, and there'll be a menu of over eighteen hundred podcasts to choose from. And if you're interested in the coaching program that I offer, you can learn more at programcoaching.com. Thanks for listening to this podcast. Have the rest of your week, and God bless.