Bob Lowry on Surface Cautions Every Pool Pro Should Know

Pools don’t fail just from age or weather; they fail when chemistry, circulation, and surface type don’t match. We dig into the real-world differences between vinyl, fiberglass, plaster, and pebble finishes, showing how each material changes your approach to water balance, sanitizer levels, and maintenance. From ground prep that keeps nutgrass from piercing vinyl to the warranty risks of using trichlor tablets with fiberglass, we share the practical moves that help surfaces last and water stay clear.

We talk through why vinyl and fiberglass often hold pH more steadily than plaster, and how colored plaster’s mottling can be an installation issue, not a chemistry fix. For pebble and exposed aggregate pools, we explain why texture invites calcium scale and algae, how diamond polishing reduces crevices, and why circulation time and brushing frequency matter more than quick, short filter cycles. If your above‑ground kit shipped with a tiny filter, a weak pump, and no timer, you’ll learn why upgrading equipment is the fastest path to clarity and chemical efficiency.

Our central takeaway: set free chlorine based on cyanuric acid, not a fixed chart. Aiming at 7.5 percent of CYA offers reliable algae control even in high‑stabilizer water, and adding borates to 50 ppm makes it harder for algae to start in the first place. Pair this with thoughtful calcium targets—lower for vinyl and fiberglass, higher for plaster—plus consistent pH control and solid circulation, and you’ll prevent stains, scale, and blooms before they begin. 

• Prep and support for vinyl liners, including nutgrass control
• Why acid damages vinyl color and trichlor tablets stain fiberglass
• How vinyl and fiberglass differ from plaster in pH and alkalinity behavior
• Target calcium levels: lower for vinyl and fiberglass, higher for plaster
• Undersized equipment in above‑ground kits and smart upgrades
• Pebble challenges with calcium and algae and how polishing helps
• Circulation time, brushing and robotic cleaners to stop footholds
• Chlorine as 7.5 percent of

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Chapters

• 0:00 Setting The Stage: Surface Types
• 3:23 Vinyl Pool Prep And Support
• 6:03 Fiberglass Speed, Warranties, And Acid Risks
• 9:23 Chemistry Differences: Vinyl vs Plaster
• 13:44 Colored Plaster Limits And Expertise
• 16:54 DIY Vinyl Owners And Undersized Equipment
• 20:34 Pebble Surfaces: Calcium And Algae

Transcript

SPEAKER_01: 2:01

Food Lowry of course is the premier chemical expert in the pool industry, and you have some great insights on how to protect different full surfaces from damage, from chemicals, and from, of course, poor water balance. Are you a full service pro looking to take your business to the next level? Join the Fool 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 swimmingfullearning.com. Let's talk about surface types. We mentioned in the startup the different startup methods, and we didn't really touch on the surface types because I wanted to leave it for a separate recording. There's all different precautions and care methods for the surface type. And let's start with one that is becoming very popular because of the cost of pools nowadays being built, and the fact that if you want a pool, probably the cheapest one you can get is a vinyl, maybe above-ground pool or in-ground liner pool, is less expensive than a full plaster or pebble tech pool. So, what are some of the things to look for when you're getting a vinyl pool or an above-ground pool installed?

SPEAKER_00: 3:14

Well, you know, I think that the the preparation uh of the of the area where the pool is going to be is really important. And so they they need to make sure that you've got a a solid bed for it, that they they put the proper stuff underneath the the bottom of the pool so something doesn't grow up through the ground and grow into your pool. And one of the biggest causes of problems is what they call nutgrass. And uh nutgrass can grow right through the vinyl and right into your pool. It's pretty tough stuff. But uh, you need to just make sure that the preparation is right, and then there's any number of methods that they use for the form that goes around the pool to hold the pool up. And whether it's in ground or on ground, there needs to be a support system for the vinyl. After all, the vinyl is just a piece of vinyl. It's only by I don't remember the thickness, but it seems to me it's like uh uh an eighth or three sixteenths, no, an eighth, you know, about an eighth of an inch thick or or less. So it is uh, you know, a membrane, and it's gonna fit inside of something, and then that something has to be supported. And you want something that will last um so that it doesn't deteriorate or whatever, and there's steel and there's fiberglass and there's you know different things that they use to hold the structure up. Getting the vinyl in the pool is really important where the seam is and where it meets the very top of the pool where the coping is, how it how it attaches at the top so that it doesn't come loose. And remember that it is vinyl, and so sharp objects in the pool can tear the vinyl and allow water to get behind it, and then you have some serious problems.

SPEAKER_01: 5:18

And you know, along with vinyl is fiberglass, it's also less expensive to drop in the fiberglass shell than to build a pool. And chemically wise, I find that the vinyl and fiberglass pools tend to hold pH better and hold chlorine better. I don't know what the reasoning behind that is.

SPEAKER_00: 5:36

Well, I'm not so sure that there's a reason for chlorine lasting longer in a vinyl pool, but certainly um pH and alkalinity. Uh, you know, in a in a plaster pool, you've always got a little bit of plaster and alkalinity coming out of the plaster into the pool. And with a vinyl pool, you don't have that happening. Uh, you know, vinyl, vinyl is plastic. It's the same thing we put, you know, water in plastic bottles and you know, chemicals and everything else. It's pretty pretty good stuff. The problem usually is that it's not very thick. But um, fiberglass pools are becoming more and more popular, especially because you can you can dig a hole, drop it in the drop it in, and be done. Uh the time from ordering a pool to when you can dive into it can be less than 30 days in some cases for for a fiberglass pool. You know, if you're gonna do a a traditional pool, you're probably looking at six or eight weeks to build it.

SPEAKER_01: 6:45

You know, yeah, and then more with the I was gonna say with the fiberglass too. I know that a lot of the builders will avoid the warranty if the customer uses trichlor tablets in there.

SPEAKER_00: 6:56

It seems like the the vinyl and the fiberglass are subject to more problems with acid than anything else. And when I had a lab and when I was at Leslie's some years ago as their technical director, you know, I was able to do some things in the lab just to try them out. That's what chemists do. You know, and I took pieces of vinyl and I dropped straight chlorine on it. Never bleached it, never did anything to it. One drop of acid and the color was gone. You know, and and actually that kind of surprised me. Um, because I, you know, my logic thinking tells you it should be the other way. You know, chlorine is an oxidizer, it's a bleach. You know, you put it on vinyl lets you breach bleach the color out. Didn't do it. But but one drop of acid on it and the color disappeared. It was white.

SPEAKER_01: 7:52

Yeah, and with the fiberglass pool with a tablet, if it were to fall in there, it would leave a permanent stain.

SPEAKER_00: 7:57

Yeah, it would probably leave a permanent stain, and it may even blister the the pool where it fell in there. No question about it. And I I've had people send me pictures and they go, oh gee, the you know, the homeowner took two uh chlorine tablets and threw it in a pool. I go, that's permanent unless you want to re-gelcoat the pool.

SPEAKER_01: 8:18

So with the vinyl and fiberglass, I think the you mentioned that the plaster pool creates its own acid demand kind of. With the vinyl fiberglass pool, the problem that I have a lot is that VPH is always pretty low in there, even without using the tablets. Right.

SPEAKER_00: 8:32

That this is true. There there isn't any outvalidity that's that's reaching into the pool. So um we do say that you know I I do promote a system of using targets, but the the target for calcium arganus in a plaster pool is 350 parts per million. And I think the PHTA guideline is 200 to 2 to 400 ppm. But for vinyl, um I recommend 250 parts per million. We don't need uh that much calcium in there. We don't we're not trying to prevent the calcium from coming out of the walls. We don't need it. Um so we use a 200 or 250, but you know, many of the areas where they have vinyl pools they don't even check for calcium. They just fill the pool up and check pH and alkalinity, and that's it. And you really need to be checking all the things. You need to be checking sanitary acid and metals and everything else, just like you do every pool.

SPEAKER_01: 9:33

Yeah, this, you know, plat, like we mentioned that plaster pools are probably the most popular still. And what are some of the the issues you can have? We mentioned in the startup, the startup issues you can have with plaster pools. One thing that I noticed is a a lot of the colored plaster pools are susceptible to modeling, you know, the color kind of patterns in there that you see. Yeah. Um, is there a way to even prevent modeling from happening? Or does is there a consensus of what actually causes that modeling in the pool?

SPEAKER_00: 10:02

My expertise pretty much stops at the water. Yeah. And and my former partner, uh Greg Garrett, was a master at surfaces. And he could look at a surface, he could lean down in a pool and rub his hand on it and tell you exactly whether it was troweled right, if they put too much accelerator in it. You know, I mean, he could tell you everything about that pool, uh, everything about the surface of that pool. Me, I look at a pool, I go, that's nice, you know. And so um, if there's I don't know what causes nodules, what causes trawling marks, what causes delamination, all those other things that get into the surface of the pools, that is a whole subject. And you could spend a lifetime like I have done uh figuring out surface problems, and I've chosen to take care of water problems. So uh I don't know uh whether there's something you can do or not do to prevent modeling of uh colored surface plaster. I I couldn't tell you that.

SPEAKER_01: 11:11

Yeah, so your expertise, of course, is the chemistry part, and you know, to focus on chemistry, uh you have most of your literature is for plaster surface pools, you know, the balancing of it, target ranges, because those are the most popular. And I think that's what you focus on, right? In your in your literature.

SPEAKER_00: 11:29

We do, and and you know, many vinyl pools are are not as expensive as plaster, and we find a lot of people want, you know, to take care of their own pools if they have vinyl versus somebody that has a plaster pool that spent a lot of money on it. They can have they afford to have somebody wash their car, clean their house, and clean their pool. You know, they they they they pay people to do that, you know. Yeah, but uh uh, you know, the vinyl guys, especially the above-ground vinyl people, they might have spend, you know, anywhere from two to five thousand dollars on a pool, you know, and they don't want to have to pay somebody, you know, hundred or two hundred bucks a month to come and clean their pool.

SPEAKER_01: 12:33

One of the things that I notice about the above-ground pools, and this is just from the service end of it, is that, well, first of all, the manufacturer can't ship full-size equipment in the box when they sell them at you know, Costco or Walmart. And so you have this extremely small filter. I mean, I've seen cartridge filters as small as 15 square feet on a you know, five or ten thousand gallon above-ground pool that they sell. And maybe a one-eighth horse horsepower pump if you're lucky. Yeah, and no timer. So I think the first thing you want to do is upgrade your equipment, right?

SPEAKER_00: 13:06

Absolutely. You know, that I don't think I've seen one of those package pools that ever has the right size equipment, ever. You know, because they're trying to keep the cost down. You know, they're trying to sell you a package for$2,000. They can't put$1,000 worth of equipment on it. So the first thing you need to do is upgrade that. I haven't even seen, you mentioned a little small filter. I've even seen a paper filter. It's not even polyester, it's paper, like you use on a on a carburetor in a car. It's made out of paper. And and that means that's like a coffee filter, man. That's not that's not very much filtration at all. And and the thing is barely you know, turning over any water, you take you three days to get one turnover in your pool. And and those above-ground pools don't have a main drain. And so all the stuff that gets to the bottom never makes it in, never gets sucked into the filter to be filtered out.

SPEAKER_01: 14:08

Yeah, that's so true. And I think that's one of the issues people have with above-ground pools is the equipment versus chemistry. And then the last surface type, and it's really popular in California, are the pebble tech or pebble sheen surfaces. And pebble tech basically is just rock. And I mean, is there any kind of I know for me in my area, the two number one problems I deal with with pebble tech is a lot of calcium buildup on the pebble and also algae getting inside the crevices a lot. Um, I don't know if, you know, is that when you consider those very common problems in the pebble tech?

SPEAKER_00: 14:43

There are some companies that when they make the exposed aggregate or pebble tech type of finishes, they actually get a diamond sander and sand that stuff to where it's smooth instead of just exposing the aggregate and then dissolving the cream that's on top of the the uh the aggregate. They actually polish it with a diamond sander. And when they do that, it has a lot less of that that getting algae and getting calcium into those crevices. There's not much you can do about that except from a maintenance standpoint. You need to make sure that the filter is on or the circulation system is on long enough to keep the sanitizer moving around in the pool. Because if you have a quick turnover, that means the water is sitting idle for many hours. Bacteria or algae can use up the sanitizer in the area surrounding it. And if there's no water movement, then it can grow without without new sanitizer being replaced and it can flourish. So you need to keep the water moving in those pools, and you also need to either use a cleaner that um can do can brush like a robotic cleaner, or you need to brush the pool once or twice a week to keep that stuff from getting uh a foothold, if you will, into the into the pebble finish.

SPEAKER_01: 16:18

Yeah, because in a pebble tech pool, once the algae gives a foothold, it's a real battle to remove it. So I think those suggestions to keep the water moving and keep it from happening in the first place are key because if you are if you're a service person out there and you've had a pebble tech surface pool that had an algae bloom, it's twice or three times the amount of work to clear it up because of the colour.

SPEAKER_00: 16:40

Well, it really is. And and I have been a proponent for a number of years about keeping a chlorine level that is different from what the PHTA recommends. They recommend a level of 2.0 to 4.0 parts per million of free chlorine in the pool, and that doesn't always work. And my recommendation is to keep a chlorine level in the pool that is 7.5% of the cyanuric acid. And and this is for residential pools only, but it is a way to make sure that algae doesn't grow in the pool. And the problem is that many times you don't have sufficient chlorine in a pool to kill the algae. And if you've got, for instance, if you've got say 80 parts per million or 100 parts per million of uh cyanuric acid in the pool, you actually probably need about seven or eight parts per million of chlorine. I'm sorry, you need about five or six parts per million of chlorine in the pool to keep algae from growing. But the PhDA guidelines is two to four. I'm a little bit at odds with them, but I've done a lot of research to try and figure out what the level should be. And the consensus is that you that you need at least five percent of cyanuric acid. So that's the minimum. And the proper level is probably 7.5. And if you use uh borate in your pool, you can lower those levels again uh because they prevent algae.

SPEAKER_01: 18:28

Yeah, we'll uh you know a basic example would be if you have a pebble tech pool, and we'll just keep it really basic. If you have a cyaneric acid level of 100 parts per million, then you're gonna need a free chlorine level of 7.5 parts per million, is that correct? That's correct. And so if you're getting algae in your pebble tech pool, it may be because you don't have enough free chlorine in there, and that's where you're getting the algae booms from. So I agree with you. I think your analysis of the chlorine level is much more accurate because I've dealt with pools with high cyaneric acid levels. They get algae and get things like that. And when you raise it above a level that you think is astronomical, it does actually, or maintain it at that level, 10 parts per million, everything is better. And I think that that kind of um proves the point that the high cyaneric acid level is a major factor.

SPEAKER_00: 19:18

It really is, and and and also too, on a pebble tech pool, I would recommend putting borate in the pool at 50 parts per million, because one of the one of the characteristics of borate is that it prevents algae. It is not an algae side, it doesn't kill it, but it prevents it. And this is what you want to have happen is to have the borate in the pool so that when the algae tries to get to start growing, the borate kills it, prevents it from from starting. And so using borate and keeping a proper chlorine level in a pebble pool is uh is the right thing to do.

SPEAKER_01: 19:58

If you're looking for other podcasts, you can find those by going to my website, swimming for learning.com, clicking on the podcast icon. There'll be over 1800 podcasts for you there to download and listen to. And if you're interested in the coaching program that I offer, you can learn more at PoolGuyCoaching.com. Thanks for listening to this podcast. Have the rest of your week. God bless.