Pool Plaster Problems You'll Get Blamed For

A pool finish can look “ruined” overnight, yet the real cause might be completely normal plaster behavior. I walk through the plaster problems that trigger the loudest complaints, the ones that quietly build over months, and the ones that only show up years later, right when the pool service pro is the easiest target. If you’ve ever inherited a pool with weird discoloration, streaks, or blotchy shading and felt your stomach drop, this conversation is for you.

We talk about plaster modeling and why mottling is often a natural part of cement-based pool surfaces, especially with colored plaster. I share why startup water chemistry matters so much, including what I’ve seen when total alkalinity is left too low after an acid startup or hot startup, and why I prefer a traditional pool startup with heavy circulation. You’ll also hear what white spotting and spot etching can look like, plus how trowel marks, dye batch changes, crazing, and localized etching can come from application, mix, or curing conditions rather than weekly maintenance.

Then we get practical: the fill-day mistakes that can permanently mark new plaster, like shutting the hose off before the pool reaches the tile line or using the autofill and leaving a runoff stain. Finally, I cover late-blooming issues like calcium nodules and why they can appear two to three years after the build, plus the pebble finish rust spots that start like algae but may actually be metal in the pebble and need a manufacturer repair.

If you work in pool service or you’re a pool owner trying to make sense of surface changes, subscribe, share this with a friend who’s dealing with plaster drama, and leave a review with the plaster issue you want me to tackle next.

I break down the plaster changes that make pool owners panic and why the service pro often takes the blame even when the cause traces back to startup, workmanship, or the material itself. You’ll learn how to recognize normal plaster modeling versus real defects, plus practical steps that reduce risk on new builds and protect your reputation.
• why plaster discoloration often gets pinned on the service company
• how modeling in plaster shows up over time, especially in colored finishes
• why low alkalinity during startup can accelerate mottling
• traditional startup basics, including high circulation and keeping chemicals in range
• white spotting and spot etching tied to mix chemistry and microcracking
• trowel marks, dye batch lines, crazing, and etching as workmanship or mix outcomes
• fill-day mistakes that create permanent rings, streaks, and hose marks
• curing risks like leaves, footprints, and pet paw prints becoming permanent
• calcium nodules that appear years later and why they are hard to “prove”
• pebble finish rust spots caused by metal in pebbles and how to get them fixed
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Transcript

SPEAKER_00 1:02

Hey, welcome to the Pool Guy Podcast Show. In this episode, I'm going to talk to you about some different things with plaster. I'm not going to say defects, but there are some things that may look like defects, and they may be defects as well. But plaster is interesting. Pool surfaces are very interesting, and a lot can happen to affect the look of it, whether it's caused by chemicals or by the initial build. I'll go over some things here for you. 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 know a lot of pool pros worry about

Why Plaster Looks Wrong

SPEAKER_00 1:51

plaster problems and being blamed for them. And this does happen out there when you take over a pool, there's maybe this coloration in the plaster. The first person they're going to turn towards is you because you're servicing the pool, you're kind of holding the bag. And it could be six months down the road or one year from the build, and all eyes are turned on you, unfortunately, because you're the one kind of driving the vehicle. It's kind of like if you went back to the dealer after a year and said, Hey man, this car has these, you know, all these problems. And and the first thing they're gonna think is, Well, it's not the car, it's the driver of the car. You know, how do you drive the car? Are you maintaining it? And that's why everyone looks at you as a pool service professional as the person who is in charge of the plaster or the surface of the pool if it's not plaster, and if it's

When The Service Pro Gets Blamed

SPEAKER_00 2:37

a problem, you're first in line to take the heat. Now, I know that it's logical to tell the customer this, and I've used this before many times. I I'll tell the customer, look, I've been doing this for a long time, and I have a lot of pools in the area, and I haven't had this problem. And if I was maintaining the pool poorly, if it was my fault, then 20 of the pools on my route would look just like yours. Unfortunately, only your pool has this problem. And if you want, I can give you addresses of pools to look at that were built similar time to yours. Hopefully, you have some kind of newer bills on your route. And you can just direct them over there to see those pools. And usually the customer that you're servicing will have no problem. Just explain to them that you have a customer that has a problem with their pool, they want to see their pool or the other customer's pool that you're talking to to kind of compare and contrast, and they'll be perfectly fine with that. Everyone loves showing their pool off to other people, and that's kind of how I logically explain to them that if it was me, every single pool would look like that or have that problem. Now, hopefully, it's not a problem where it gets to that level to where you have to send the customer looking at other pools or where you know you're threatened by lawsuits or you know, other things at that high level, which it can escalate to that point. I've had a pool or a couple pools where it got to the point where you know the customer's like, oh, I'm gonna sue you your company or whatever. And it's one of those things like I actually had a friend who actually sued the builder, and this was many, many years ago. He had a he had a pool built by this builder, and it had these discoloration streaks in it. It was a color plaster pool. And if you have a color plaster pool, if you take care of one, you know that they're gonna have a lot of discoloration. But these were kind of weird. They showed me the picture of it. This again was several years ago, and it had like these darker streaks down the deep end. I almost looked like for some reason when they filled the pool, somehow water, I don't know, from a garden hose or something went down the size of it before it was filled, but that's unusual. You know, the builder usually will fill it with the towel and a garden hose on the bottom of the deep end, but it did look like some water got on there before it fully cured, and that's why I had those streaks. Well, anyway, he went to court, he actually went as far as the court with it, and the judge looked at the photos and looked at everything, and he's not a builder, he's not a pool professional or any kind of anything in that regard, and so that's the danger, or that's the benefit, I guess. When you go to court, the builder, of course, had all the documentation, showed everything, wasn't you know anything that he did in the build. And the judge didn't have enough evidence to rule in the favor of the pool owner because you know the judge is a judge, he has to make a judgment based on the evidence and based on what he sees, and he's not an expert. And to him, that looked just like normal, you know, discoloration of the pool. And it was pretty, in my opinion, was a pretty bad discoloration, and and the pattern again was kind of like a streak pattern. So obviously there was a problem, but you have to really have a case that's you know 100% bulletproof. If you you went to court and there's like big old holes in the plaster, you know, two feet holes cracked everywhere, then yes, you do have a case there. Uh, there was actually another case where I know a builder here in Los Angeles, he built an infinity-edged pool and it started actually sinking, which a lot of them do sink by the way, but this one was sinking more than like anything you would ever see before. And I think it was sinking like one or two feet, it was like a crazy amount, was cracking. Of course, the builder lost that lawsuit and he had to pay $250,000, or insurance had to pay that to redo the pool. And it was just bad engineering at that point, it wasn't the builder's fault, but it was the engineer he hired, and the hillside could not sustain that pool. Anyway, I just want to let you know that unless there's something really obvious, your fault, like if you pour two gallons of acid in the pool and you know you run the pool and it just totally destroys the plaster, it's really hard to go that far all the way to court, and most people don't go that far to court over you know, discoloration of the pool surface. So now that I got the scary stuff out of the way, basically there are just a few things that are really defects of the plaster, and the modeling of the plaster or the discoloration, like the pattern, kind of like a top graphical map, is pretty normal in plaster, much more evident in color plaster. It's called modeling. Now, I think a lot of times what brings this on, in my opinion, is low alkalinity in the pool on the startup is one thing that really makes the modeling present itself faster than it normally would come out in the plaster. What I like to do when I start the pool is to keep the alkalinity like right around 100. That way that eliminates that factor because I've seen pools I've taken over right after the pool was built, after the startup, where the alkalinity

Modeling And Startup Chemistry

SPEAKER_00 7:37

was like 30. And this could happen if they're doing like an acid startup or a hot startup and they never really adjust the alkalinity back up correctly. And I I feel like this leads to a lot of the modeling of the plaster. I'm not an expert. You can go to the National Plaster Council, look up articles on it, different articles, but I have seen evidence that low alkalinity does cause this. So as long as you keep the chemicals in range on startup, you should have no problem. My my ideal startup would be to run the pool 24-7 for a week just to keep that thing circulating like crazy. And it seems to be highly effective to do a traditional startup. It's the easiest one to do. You can go to the National Plaster Council website and see the traditional startup or just Google traditional pool startup. And I really like running it a long time because I feel that really helps everything when the pool is just continuously running. And I've seen pretty good results with pools that are running a lot. Now, a lot of times the modeling will happen because they have a bad startup. I was at a pool where they had finished it, filled it, but the electrician, for whatever reason, was behind, and he actually never wired up the equipment, so it was just sitting there all unwired, unpowered. And so the pool had water for about 10 to 12 days in there with nothing running. That pool did have some serious modeling issues, also some calcium issues later because of the plaster dust. It was just a big mess. But unless there's a catastrophic failure of subcontractors, typically the modeling will just something will be something that just happens to the plaster over time. You know, in a year or two, you're gonna see this some slight discolorations. And I always tell people, you know, look at the sidewalk when you're walking. You can you can see that the cement has discolorations in it. It's just a natural thing when you're using a plaster mix. In fact, a lot of builders won't even warranty white plaster because of the discoloration that can happen in it and the variations of the color of the white plaster. So the normal discoloration or modeling is not a defect in plaster, in my opinion. It's just something that naturally occurs in plaster. White spotting is something you're gonna hear about. This is when you're gonna see white or dark dark color spots in the plaster. It's called spot etching as well. And this is basically there's a calcium chloride mix in the plaster, and this really contributes to the plaster being porous on a microscopic level, and then shrinkage and microcracking of the surface area. So this can happen on a pool build. It's not something that can be controlled usually by anything, but it's something that leads to some kind of you know spotting in the pool. You'll see it if you've seen it before, especially with a darker colored plaster pool, you'll see some really light areas of that pool, and that's probably what that is. Discoloration, of course, is something that could happen if you're using colored plaster or even white plaster, and it's it's like modeling, but there can be some things that

Spotting Trowel Marks Crazing Etching

SPEAKER_00 10:59

you know there can be some trial marks or trowel burns if they're you know if they're not careful with the surface when they're doing it. And it's one of those things where you can see some of the marks on there. I I had a pool that was built, and you can see a lot of the trail marks on the steps where they weren't really, I don't know if they were not moving fast enough or they just were kind of sloppy. But it is an art form doing the plaster by the way, and it is a skilled job, and you can mess it up. I have one pool, and this is one that was the only one I've ever had like this. They it was a dark-colored plaster mix. They had plastered most of the pool up to about the sh, you know, halfway in the shallow end, and then from halfway in the shallow end to the steps, it's much darker, and you can actually see a line in the pool. And I asked the customer, well, what happened to your pool? He said, Well, they ran out of the dye for the plaster, and they had to mix a new batch, which is kind of weird, but you know, if you're not experienced it could happen, I guess, and so that's why there's two different colors in the plaster of this pool. Here's one that I've seen also in pool builds here. It's called crazing or cracking, and this is when there's an excessive amount of shrinkage in the surface area, and you know, germinal will get in there, and it's one of those things where crazing can result from drying the plaster before the pool is filled, and so you know, and it could also be also excessive calcium chloride in the mix. So these are all things that can cause some weird-looking patterns on the pool, and I've seen this as well. Again, a lot of these are things you're gonna have to see out there when you're doing the pools, and you have etching also, is something that you'll see. Etching of the plaster is you know, there's some soft spots or some degrading of it. You know, usually I've seen this around like return jets before, where you've had this problem where it wasn't really done well, and then the return jet has you know some some real a real-looking defect uh of the plaster, and sometimes you know, it can just be basically the application or the mix of the plaster that causes that. So, you know, just understand that you may see trial marks. I've seen footprints in the pool before myself as well. I've seen this one, and this one is one that can be avoided, but it does happen out there, and that is when the pool is being filled, the customer should never turn the pool water off until it's completely filled all the way to the tile line. It doesn't really matter, I think, the speed of filling. It's just if it does stop for a period of time, let's say 10 hours or so, and the customer did this, they were going to bed, they don't want to leave the water running, and so about one and a half feet from the tile line, they turned off the water. Next day they continued filling it. But what would happen is that that top area of plaster was exposed, and the line where the water had stopped, when they continued filling it, there was about a half-inch line around the whole entire pool of discoloration from that moment, and it was impossible to get rid of. The builder did a zero alkalinity treatment and it

Filling Mistakes That Leave A Line

SPEAKER_00 14:12

looked a little lighter, but that line is probably still there till this day because it can't be removed once you do that. So never turn the water off when the pool is filling, even for an hour or two, because that could leave that mark. I was at a pool also where they use the autofill to fill the pool, and from the autofill into the pool, you can see a discoloration where the water ran down the side of the pool into the pool. And of course, you don't want to use the autofill to fill up a new build. You want to make sure you put the garden hose in the bottom and at the towel, and that way you're filling it without leaving any marks or mars on the bottom. I've also seen the bottom of the deep end that had kind of like those discolorations all by the main drain. And apparently, I guess the hose was moved a few times and didn't have a towel on there for whatever reason, and it left those marks as well. The plaster, why it's curing, is very malleable. It's kind of like if you were at a you know, you were on the sidewalk and they put a new cement slab in and you put your name in there, you know, you stepped on it. Same thing would happen to the pool plaster in some respects, it's still curing and it's still pretty soft, so anything could cause that kind of problem. I even had a new build where they had a hacaranda tree over it, and it was in the time when it was dropping those little tiny, you know, half what it millimeter type leaves everywhere, and a bunch of those got into the pool. Now, what once the pool plaster cured, you know, most of the staining was we were able to remove, but there were still you could still see tiny little uh leaf marks all through the shallow end of the pool, which never went away. Another one, a dog got into the step area, stepped in there. You can see the dog paws on the plaster. So as it's curing, it's very malleable. One of the most common defects that I see here in my area is calcium nodules, and these are deposits in the plaster. Usually it comes out when you know two or three years after the pool build. So it definitely looks like you're at fault because you've been doing the pool for two or three years, and you're gonna see these kind of raised white marks in the pool, almost like I don't know, they're just calcium basically deposits, but they look maybe the size of a nickel or a quarter, and they look like something you would see in a cave, they're coming out of the plaster itself, and these bumps are pretty much can form anywhere on the side of the wall or on the bottom. And the problem is that there's small cracks or voids in the plaster, and then the calcium-rich water seeps into these cracks, and then over time, two or three years, they form in there, and that's where you get the calcium nodules forming in the pool. And that isn't your fault, and it's kind of the builder's fault,

Calcium Nodules And Rusting Pebbles

SPEAKER_00 16:53

but it's been a long time, so it's one of those hard ones to kind of say, Hey, the builder, you know, when they were plastering it, there's little pocket pockets in there, and this is where the calcium's forming. Really hard to explain that to the customer. I had one that was really bad where the deep end had like 20 of these, and they were really, really obvious. The best you can do is maybe use a rust stone to kind of scrape it down and make it flush to the surface, but they're gonna probably come back over time because there's actually a small little hole in the plaster. Oh, and with this defect that I get, I've been getting a lot of messages from Arizona about, and I would assume that maybe in Arizona they got a bad batch of pebble tech, but pebble tech is river rock, and if you they use a magnet to kind of make sure there's no metals in there when they're manufacturing it. Some of these, some of the rocks with metals does get through in certain areas. There was a bad case of this in Hawaii, like a decade ago. Here in California, there's been a couple bad cases where a lot of pebble tech pools built a certain year had this, and you'll see rust stains coming out. It looks like almost like black algae or green algae at first, and then they'll start to get more and more rust color, and they can be the size of a pencil eraser up to the size of a quarter, I've seen. And basically, that's just the metal and the pebble. The way to cure that is to call pebble tech, they'll send someone out there and they'll chip those bad pebbles out of the pool. And it's a defect that does pop up ever so often in different areas, and I think right now it's in the Phoenix, Arizona area at this moment, so just keep an eye out for pebble tech when you see what may look like black algae or green algae, and then over time it starts to get more rust color and looks like a metal stain. It's probably a bad pebble with metal in it, and it's something that can be pretty easily corrected by pebble tech with their technicians. But I just went over a few of the kind of defects you may see in plaster, and mainly you're not gonna have too much trouble out there, and you know, the plaster companies are doing the best they can with what they have, and it's one of those things where who's to blame who, and a lot of times, really no one's at fault, it's just the plaster itself curing over time. The discoloration and modeling to me are normal for plaster now. And if you really wanted a pool with no discoloration, I would always say go with pebble tech, but then you're gonna get some calcium buildup in there, it looks like discoloration. So there really isn't a surface type besides vinyl and fiberglass where you're not gonna have some kind of discoloration or variation of the plaster or pool surface itself. Looking for other podcasts, you can find those by going to my website, swimmingpoollearning.com. And if you want more podcasts, click on the podcast icon. There'll be a drop down menu

Choosing Surfaces And Final Advice

SPEAKER_00 19:36

of 1900 podcasts for you there. If you're looking at my coaching program, you can learn more at poolgatecoaching.com. Thanks for listening. Have a good rest of your week. God bless.