INFORMAZIONI SU QUESTO EPISODIO
Algae every week even though the test kit shows plenty of chlorine? That headache usually isn’t bad luck, it’s bad math. We dig into the most common rookie mistakes new pool service pros make and show the chemistry behind why a pool can read “sanitized” while algae still wins. The big unlock is understanding cyanuric acid (CYA) and how it binds most of the chlorine in the water, leaving only a small active portion available to kill algae.
From there, we make the fix practical: stop guessing and start targeting free chlorine based on your stabilizer level. We walk through the easy field rule that free chlorine should sit around 7.5% of CYA, plus how adding borates at about 50 ppm can lower that requirement to roughly 5% in many pools. If you’re servicing trichlor pools with high CYA, this framework explains exactly why “6 ppm is high” can still be nowhere near enough.
We also shift from pure chemistry to water balance and operations. We talk about the Langelier Saturation Index (LSI), what it’s designed to predict (scale forming vs corrosive water), and why “balanced” isn’t the same as “stable” when alkalinity and pH are constantly drifting. Then we hit a nuts-and-bolts issue that ruins otherwise good chemistry: filtration runtime. We explain turnovers, why one turnover only filters about 65%, why three turnovers is a smart target, and how low circulation creates dead zones where algae can grow.
If you want to tighten up your pool maintenance results, reduce call-backs, and run a more predictable pool service business, listen through and take notes. For more training, visit swimmingpoollearning.com and check out PoolGuyCoaching.com, then subscribe, share the show with a tech who needs it, and leave a review so more service pros can find it.
We break down the most common rookie mistakes that keep new pool service pros stuck in recurring algae, cloudy water, and constant chemical chasing. We show how to set smarter chlorine targets using the cyanuric acid ratio, when borates change the math, why LSI can mislead if you ignore stability, and how pump runtime and turnovers make or break circulation.
• misunderstanding how high cyanuric acid weakens effective chlorine
• using the 7.5% of CYA free chlorine target
• lowering the chlorine requirement with 50 ppm borates
• why “2 to 4 ppm chlorine” can fail for algae prevention
• what LSI predicts and what it does not
• choosing target ranges to make water stable week to week
• calculating turnovers from pool volume and flow rate
• why short runtimes create dead spots and let algae take hold
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IN QUESTO EPISODIO
MOSTRA NOTE 🔗
TRASCRIZIONE 🔗
00:01:04.659 --> 00:01:07.780
Hi, welcome to the Best of the Pool Bay Podcast Show.
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In this episode, Bob Larry's going to go over some common mistakes you make as a new Pool Service Pro.
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We'll call them rookie mistakes.
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He'll go over these in detail for you here.
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And of course, you're going to glean a lot of knowledge from what Bob Lowry has to say in today's episode.
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Are you a Pool Service Pro looking to take your business to the next level?
00:01:27.539 --> 00:01:29.140
Join the Pool Guy Coaching Program.
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Get expert advice, business tips, exclusive content, and get direct support from me.
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I'm a 35-year veteran in the industry.
00:01:36.900 --> 00:01:40.659
Whether you're starting out or scaling up, I've got the tools to help you succeed.
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Learn more at swimming poollearning.com.
00:01:43.859 --> 00:01:46.900
Let's talk about some rookie mistakes out there.
00:01:46.979 --> 00:01:58.020
Now there's a lot of new people in the industry, or you may be an employee coming on to a pool company, and we'll go over some of the top mistakes I think people make in the industry when they first start.
00:01:58.180 --> 00:02:08.340
And I think number one, and this is also happening even with the old school guys out there, is not understanding the effects of high cyaneric acid on chlorine.
00:02:08.740 --> 00:02:18.819
And then on the second part of that, you know, how important the cyaneric acid and free chlorine ratios are, and something that a lot of people don't consider.
00:02:18.979 --> 00:02:34.500
And so they'll have a trichlor pool that has cyaneric acid of maybe 150 or 200, and they're getting algae in there every week, and the free chlorine levels at you know five or six parts per million, and they're scratching their head thinking, hey, there's tons of chlorine in here.
00:02:34.659 --> 00:02:36.740
Why am I still getting algae in this pool?
00:02:36.900 --> 00:02:40.500
So you want to go over kind of this misunderstanding that happens out there?
00:02:42.180 --> 00:02:49.780
For years we used to just put in two to four parts per million of chlorine in the pool, and that was supposed to be enough.
00:02:49.939 --> 00:02:58.259
And then every summer we all battled algae and put in algicides and superchlorinate and shock once a week and all those kinds of things.
00:02:58.500 --> 00:03:05.459
And and we were doing stuff weekly to bring the chlorine level up to where it would kill the algae.
00:03:05.780 --> 00:03:09.620
We started figuring out what the problem is.
00:03:10.099 --> 00:03:18.340
And and about eight or nine years ago, I spent a few hundred hours studying what's what's going on in the pool.
00:03:18.500 --> 00:03:29.060
And the good news is that because I'm independently wealthy and independent, if I want to spend 200 hours doing something, I don't have a boss telling me I can't do that.
00:03:29.379 --> 00:03:35.219
So I studied it to find out what kills algae, how much chlorine we need.
00:03:35.459 --> 00:03:49.459
Depending on who you talk to, we need only between 0.3 and 0.5 parts per million of HOCL in the water.
00:03:49.859 --> 00:03:54.340
And the some people disagree with the 0.3.
00:03:54.819 --> 00:04:05.219
I mean 0.03, but everybody would agree that that 0.05 parts per million HOCL will kill algae.
00:04:05.539 --> 00:04:15.539
So if we know that, then we're able to calculate how much chlorine is in the water if we know how much cyanuric acid is in the water.
00:04:15.859 --> 00:04:22.420
So we started figuring out how much cyanuric acid, how much chlorine is in the water.
00:04:22.579 --> 00:04:37.860
And the fact of the matter is, even with only 30 parts per million of cyanuric acid in the water, 97% of all the chlorine that's in the pool is bound to cyanuric acid.
00:04:38.100 --> 00:04:39.939
It's attached to it.
00:04:40.340 --> 00:04:45.860
And it's not like it's not available, but it's not available right now.
00:04:46.259 --> 00:04:54.100
Only the 3% that is not bound to the cyanuric acid is available for killing anything.
00:04:54.420 --> 00:04:59.379
That is an equilibrium reaction, 97% and 3%.
00:05:00.019 --> 00:05:09.620
So if you use some of the 3%, some of the 97 will switch over so that that 97 and 3% is maintained.
00:05:10.259 --> 00:05:27.939
But because we know that 3% of the chlorine is doing the work, we can multiply the 3% of the amount of chlorine that's in the pool and find out if we've got enough chlorine.
00:05:28.819 --> 00:05:46.019
So if you have say two parts per million of chlorine in the pool, if you multiply two parts per million of chlorine by 0.03%, okay, you and you well, let me back up.
00:05:46.980 --> 00:05:58.899
You also may know that when chlorine is in water, the pH determines how much HOCL is made and how much OCL is made.
00:05:59.539 --> 00:06:09.219
And the the OCL minus and the HOCL are at 7.5 pH is about 50%.
00:06:10.259 --> 00:06:14.980
So you got 50% HOCL and 50% OCL minus.
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So that means that only 1.5% of the chlorine that's in the water is gonna kill anything.
00:06:26.899 --> 00:06:41.939
So if we take two parts per million and multiply it times one point five percent, we get zero point three parts per million HLCl.
00:06:43.379 --> 00:06:46.980
And we said we needed zero point five.
00:06:48.259 --> 00:06:56.980
So if you're keeping the chlorine level at two parts per million in that pool, you don't have enough chlorine to keep algae from growing.
00:06:57.379 --> 00:06:59.139
And it is that simple.
00:06:59.699 --> 00:07:10.420
And if we put in three parts per million of chlorine in that pool, 1.5 percent of three is 0.45.
00:07:11.539 --> 00:07:15.620
That's not quite 0.5, but it's close.
00:07:15.779 --> 00:07:18.740
So three parts per million might actually work.
00:07:18.819 --> 00:07:20.899
It's on the maybe on the borderline.
00:07:21.139 --> 00:07:28.339
And if you multiply four parts per million times 1.5 percent, you have 0.06.
00:07:28.740 --> 00:07:31.860
And 0.06 will definitely kill algae.
00:07:32.180 --> 00:07:44.579
So what I claim in my most of the things I write, two to four parts per million of chlorine that's recommended by PHTA may not always work.
00:07:45.699 --> 00:07:51.860
And don't believe that if your chlorine level is between two and four, you're good.
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Because I just showed you that you could have two and not be good and four and be good.
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So if you're in between there, it doesn't mean you're okay.
00:08:03.300 --> 00:08:11.539
So instead of having to do the math that way, we reversed it and made it easier for you to calculate.
00:08:11.699 --> 00:08:23.939
And so the free chlorine level that you need in the pool needs to be 7.5% of the cyanuric acid level.
00:08:25.060 --> 00:08:35.300
And yes, that means if you've got a hundred parts per million of cyanuric acid in the water, you need 7.5 parts per million of free chlorine.
00:08:35.940 --> 00:08:37.220
It means that.
00:08:46.500 --> 00:08:54.259
That's their rule, and actually their rule actually never considered the fact that you would have cyanuric acid in the pool.
00:08:54.659 --> 00:08:59.779
Because your exposure to chlorine is less with cyanuric acid than without it.
00:09:00.019 --> 00:09:04.899
For that same reason, only three percent of the chlorine is available.
00:09:05.379 --> 00:09:13.220
So you're not exposed to four parts per million of chlorine, you're only exposed to three percent of four parts per million of chlorine.
00:09:13.620 --> 00:09:29.779
So the thing that you can do to reduce the 7.5 percent is if you add borate to the pool at 50 parts per million, you can lower the 7.5% requirement to five percent.
00:09:30.980 --> 00:09:34.899
And that becomes a much more manageable and easy number.
00:09:35.139 --> 00:09:42.819
5% of whatever your cyanuric acid is is how much chlorine you need in the pool to prevent algae.
00:09:43.059 --> 00:09:48.340
And if it goes below that, then you you run the chance of getting algae.
00:09:49.139 --> 00:09:53.539
And and we have we've been teaching that for three years.
00:09:53.779 --> 00:10:05.620
I've written about it now for eight years, and I've also got a book that most of you have probably heard of called Pool Chemistry for Service Pros.
00:10:06.179 --> 00:10:20.100
And it's a short book of 28 pages, but we recommend in there to keep the level of borate at 50 parts per million and chlorine level at 5% of that of CYA.
00:10:20.340 --> 00:10:30.340
But that book has now been distributed to 13,000 service techs, and they're doing it, and it's working for them.
00:10:30.580 --> 00:10:52.179
Yeah, and I would say from field testing and experience, you know, if you want to keep your pool algae-free, even with a high chlorine level, like I gave that example at the beginning, a 200 parts per million cyaneric acid pool, not unheard of in California, by the way, a six parts per million chlorine is not enough to keep the algae out, even with borates in there.
00:10:52.340 --> 00:10:55.059
So um, with the borates, you would need 10 parts per million.
00:10:55.299 --> 00:11:10.980
So if if the new guy is struggling with algae pools and he thinks he thinks that, and this chlorine level is off the charts, you know, but I'm still getting algae, that's the reason because they don't understand the formula that you just went over there in great detail, by the way, which I really appreciate that.
00:11:30.600 --> 00:11:40.519
I like the fact that you reversed it because doing the math forward is difficult for anybody, and using that easy percentage backwards is much better.
00:11:40.759 --> 00:11:43.879
And then another aspect is the LSI.
00:11:44.120 --> 00:11:58.040
Interesting, I was talking to Scott Hamilton over at United Chemical about his Hamilton index, and that's another index that you can actually use that one in California pretty effectively because of our high calcium hardness level.
00:11:58.279 --> 00:12:03.160
But the LSI is pretty much the standard of the industry across the country.
00:12:03.480 --> 00:12:10.600
And what about the pool guy that probably has never heard of the LSI, never w never thought about it?
00:12:10.840 --> 00:12:30.600
What would be the problem with someone starting out their pool service business or working for someone and not even knowing what the LSI is It actually depends if he if he got one of our books and started using targets, he probably wouldn't need the LSI.
00:12:31.160 --> 00:12:53.639
But if he just started doing pools and he's got all this mishmash of information, understand that the LSI is a method of predicting whether your pool is going to be scale forming, whether you pool water is going to be scale forming or corrosive or what we say is balanced.
00:12:53.800 --> 00:12:58.759
And it's a method of predicting whether that will whether the water will be that way.
00:12:59.080 --> 00:13:09.800
And you measure, in the old days, we measured five things and plugged those test results into an equation and got the answer.
00:13:10.680 --> 00:13:17.320
And now with the advent of cyanuric acid and borate, we now have seven things to check.
00:13:18.519 --> 00:13:31.080
We most of the time look up the seven water tests, we look up a factor for each one of those test results and enter them into an equation.
00:13:31.320 --> 00:13:37.080
And the the desired result is to come up with a 0.0 answer.
00:13:37.160 --> 00:13:43.000
And that means your water is perfectly balanced, neither scale forming nor corrosive.
00:13:43.560 --> 00:13:52.120
It is important if you're going to be maintaining water to know if you're going to be forming scale or or not.
00:13:52.680 --> 00:14:01.480
And there are various indices out there, and frankly, the Hamilton Index is not an index.
00:14:01.720 --> 00:14:05.160
They call it an index, but it's not an index.
00:14:05.320 --> 00:14:09.879
And it pretty much does only work in California and Arizona.
00:14:10.120 --> 00:14:12.680
Most of the other countries can't use it.
00:14:13.320 --> 00:14:26.279
But and if you if you use the Hamilton Index and use some numbers from it's index and plug them into the LSI, you find that it's not balanced water.
00:14:26.600 --> 00:14:33.320
So I'm not a big fan of the Hamilton Index, although it's been around for a long time.
00:14:33.480 --> 00:14:37.240
But just because it's been around doesn't mean it's a great index.
00:14:37.879 --> 00:14:42.920
But in any case, if you want to follow it, it's better than not doing anything.
00:14:43.160 --> 00:14:48.840
So I would suggest just using targets as we recommend for everything.
00:14:49.000 --> 00:14:52.519
And then you really don't need to be using any index.
00:14:52.840 --> 00:14:56.200
You're just everything is on target or it's not.
00:14:56.519 --> 00:14:59.960
And if you don't put it on target, you're gonna have a problem.
00:15:00.600 --> 00:15:01.560
Yeah, it makes sense.
00:15:01.639 --> 00:15:09.480
And I I think that that's a good answer because your target ranges, and I'm you know, more and the more and more I look at it, and I use this example with you.
00:15:09.639 --> 00:15:20.680
If you go into the bank and you tell a teller, you know, I like to get$100 out, and she says, Well, here's 80, you know, it's within range of a hundred, you're gonna walk out of the bank not quite as happy.
00:15:21.000 --> 00:15:46.519
And so the targets make a lot of sense because you're talking about you know, a hundred thousand, two hundred thousand dollar investment in some people's backyards with their pool, and you have all these ranges, and you mentioned before in a different recording that if the LSI is could be perfectly balanced in those kind of ranges that people are using, you know, 80 to 120 for alkalinity, pH of 7.4, and it may not even be balanced.
00:15:46.920 --> 00:15:54.519
Well, you can balance the water so that it you have a perfect LSI, but still not have a stable pool.
00:15:55.240 --> 00:15:57.320
And that that is the problem.
00:15:57.720 --> 00:16:00.360
And you could, you know, you could balance a pool.
00:16:00.440 --> 00:16:14.600
For instance, if you had an alkalinity of 140, you could maybe use a a pH of 7.2 with that and and have everything else in the normal ranges, and you'd have a balanced pool.
00:16:15.399 --> 00:16:25.320
But with an alkalinity of 140 and a pH of 7.2, that's only gonna stay 7.2 for you know, maybe today.
00:16:25.480 --> 00:16:29.399
You know, tomorrow the pH is gonna be 7.5 or 7.6 or 7.8.
00:16:30.040 --> 00:16:33.800
An alkalinity of 140 is gonna raise that pH like crazy.
00:16:34.120 --> 00:16:40.680
So there's a difference between balancing the pool and making it stable.
00:16:41.240 --> 00:16:51.720
And the goal is to make it stable so that from one week to the next or one visit to the next, nothing changes, or it changes just a little bit.
00:16:52.360 --> 00:16:54.040
Yeah, makes perfect sense.
00:16:54.440 --> 00:17:03.800
Another thing that we've touched on before is, you know, homeowners may not know this because they always are trying to cut their runtime down on their pool filter.
00:17:04.039 --> 00:17:13.000
That's one of the problems I have out there, is they're always telling me, I just had a customer yesterday tell me, Oh, can you reset my system so it's not running so long because my electricity bill was super high.
00:17:13.240 --> 00:17:21.319
But I think runtime of runtime of the pool filtration system is one thing that new people don't really pay attention to.
00:17:21.480 --> 00:17:29.080
You know, they may get an account where the customer has a 20,000 gallon pool running for four hours a day and they're scratching their head, you know, why is the pool cloudy?
00:17:29.160 --> 00:17:30.040
Why is there algae?
00:17:30.279 --> 00:17:33.560
So the runtime is a big deal, especially in the season.
00:17:33.960 --> 00:17:56.680
Yeah, it you know, the the fact of the matter is that that from a filtration standpoint, if if you get one turnover of the pool, and a turnover is an amount of water that's equal to the volume that's in the pool gone through the filter.
00:17:57.080 --> 00:18:00.440
So, and so it's based on water flow.
00:18:00.840 --> 00:18:14.200
So if you take the the gallons in the pool and divide it by the flow rate, then you will find out what your turnover is in minutes, assuming that your pump is in gallons per minute.
00:18:14.440 --> 00:18:20.039
So you can determine how many minutes or hours it is to get one turnover.
00:18:20.839 --> 00:18:31.240
But from a a filtration standpoint, one turnover will only give you about 65% filtration.
00:18:32.440 --> 00:18:56.920
And then if you get two turnovers, it will give you about 85% filtration, and three turnovers will get you about ninety-two to ninety-five percent, and four turnovers will get you ninety-eight or ninety-nine percent.
00:18:57.559 --> 00:19:21.240
So, what we recommend is that you get three turnovers because the difference between three turnovers and four turnovers is like three percent, it's not worth doing, but you need to get three turnovers in your pool, and you can calculate for yourself how many minutes that's gonna be, and all you need to know is the flow rate.
00:19:21.640 --> 00:19:40.839
And so you put a a rotameter or flow valve right after the pump, right out, I'm sorry, at least after the pump and and before it gets back to the pool to find out what your flow rate is, and and then all you have to do is do the math.
00:19:41.160 --> 00:19:48.200
You know, if you got 20 gallons or 30 gallons a minute running through there, you got a 15,000 gallon pool.
00:19:48.279 --> 00:19:49.799
How many minutes is that?
00:19:50.120 --> 00:19:54.360
You know, it's 500 minutes to get one turnover.
00:19:54.680 --> 00:20:00.519
And and 500 minutes is uh almost eight hours.
00:20:01.480 --> 00:20:06.759
You know, so so and if you want three turnovers, it's 24 hours.
00:20:07.079 --> 00:20:13.960
So if you if you only run your pump at 30 gallons a minute for four hours, that's not even one turnover.
00:20:15.160 --> 00:20:16.920
That's a half a turnover.
00:20:17.640 --> 00:20:25.000
So you can't possibly get get enough filtration to to have a great looking pool.
00:20:25.559 --> 00:20:34.920
The other thing is, if the if you only run your pump for four hours a day, that means for 20 hours a day, there's no circulation.
00:20:35.799 --> 00:20:51.799
And and if you have a biomass, a biofilm, or an algae starting to grow someplace, it the that mass, that biomass uses up the chlorine that's in the vicinity.
00:20:52.200 --> 00:20:56.600
And if the circulation pump's not on, it used up all the chlorine.
00:20:56.680 --> 00:21:06.680
Now it can grow like crazy because there's no new sanitizer being brought to that area of the pool because there's no circulation.
00:21:07.000 --> 00:21:10.600
If you're looking for other podcasts, just go to my website, swimming for learning.com.
00:21:10.759 --> 00:21:12.360
On the banner is a podcast icon.
00:21:12.440 --> 00:21:16.600
There'll be a drop-down menu with over 1900 podcasts for you there to listen to at your leisure.
00:21:16.839 --> 00:21:20.920
And if you're interested in the coaching program, you can learn more at PoolGuyCoaching.com.
00:21:21.079 --> 00:21:22.440
Thanks for listening to this podcast.
00:21:22.519 --> 00:21:23.480
Have a rest of your week.
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God bless.