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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1 SPEAKER_00: 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.
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I know a lot of pool pros worry about 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 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 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 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
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, 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
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Thanks for listening.
Have a good rest of your week.
God bless.