Perhaps the loveliest part of any pool install is the tile work. Whether it's a graceful Grecian, a classic kidney or a simple rectangle, a tile border frames the sparkling water and draws the eye to the pool's perimeter.
Unfortunately, many of these gorgeous, colorful works of art turn dull and lifeless when calcium scale builds, attracting unwanted attention to the tile. The good news is that with a bit of work and a good measure of chemical education, you can keep the pool tile looking like new, or bring back the brilliance once it's gotten grungy.
COMPLICATED CAUSES
Que Hales manages Pool Chlor, a residential service company in Tucson, Ariz. But that's just his day job. He also spends time consulting with an industry consortium called onBalance.
Composed of people from three likeminded service companies, onBalance conducts research on water chemistry, including the connection between pool water and pool plaster and tile. While Hales would like to say he and his colleagues there have discovered the secret of keeping calcium from accumulating on the tile line, he paints a more nuanced picture of the problem.
"We think there's a lot of misinformation in the industry," he says. "So we try to help people by pointing out when they're looking at something the wrong way."
In this case, he tells anyone willing to listen that trying to eliminate calcium buildup on tiling is a losing proposition, because it can't be done.
Hales knows this will strike some as dangerous heresy. He's used to it.
"There's at least a possibility that when somebody hears that, they will think I'm downplaying the importance of balancing the water. But there's nothing further from the truth," he says. "I'll explain it like this: If you have calcium on underwater surfaces, it's because there was calcium in the water that was pushed out of solution for some reason, and that's called a precipitate. Usually it means either the calcium hardness level is above the recommended 200 to 400 ppm, or the pH or alkalinity is high. These are saturation index issues, and there is certainly a way of balancing the water so that it doesn't push that calcium out of the water and onto those surfaces."
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That's what managing the water balance can do. What it cannot do, he says, is totally prevent calcium buildup along the tile.
"If you look at the first quarter of an inch or so of the tile above the water surface, it's damp, and that's where the water wicks up that face and evaporates," Hales says. "Regardless of your pH or alkalinity or dissolved solids, or whatever else, once that water evaporates you're leaving the minerals behind. So again, that chemical reaction that causes calcium to precipitate is not what's happening on the water line. That's just evaporation, and what's formed afterwards is called an evaporite."
We asked Jana Auringer, the quality assurance manager for Pebble Technology in Scottsdale, Ariz., a couple of hours north of Tucson on I10, whether she shared Hales' fatalistic view of calcium's inevitability along the tile line.
"I think I do, because when calcium is on the tile, it's because it's where the warmer water is, and it's where the body oils and suntan lotion go," she says. "So it's a lot harder to prevent, and you can have good water balance and still get that deposit on the tile."
KEEPING CALCIUM IN CHECK
If eliminating calcium buildup on tile is difficult or perhaps even impossible, does that mean Hales and Auringer think service techs and homeowners should just throw up their hands and accept the problem?
Here Hales clarifies their position on the matter.
"If you can get it to the point where the calcium level in the pool is not rising that fast to begin with, then it will slow down how much calcium is available to attach itself to the tile," he says. "And the problem will be more manageable."
Some areas have the good fortune of having good water to fill pools, so mineral levels are low from the get-go. In other parts of the country, however, the water supply contains calcium (and other minerals and metals) that approaches the upper end of the recommended range. In either case, slowing the increase by maintaining balance is the best plan. The higher the calcium hardness in the fill water, the less leeway you have.
"That's one big factor right there," says Brad Cashman, president of Albuquerque Pools & Spas in Albuquerque, N.M. "How good is the source water coming into the pool?"
Once he's answered that question, Cashman, a pool veteran of more than 40 years, tests pH, chlorine, total alkalinity, calcium hardness and total dissolved solids — and then works to get the water in balance.
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"So we're kind of getting all of those things working together," he says. "You're never going to have it perfect, though, because conditions are constantly changing. Heat and bather load, for example, can be difficult to account for."
Cashman knows there's only so much he can do with scheduled maintenance, and that homeowners will have to keep an eye on things, too. He likes to start by teaching pool owners a little chemistry lesson, always careful not to throw too much at them and scare them away.
"We start them out with testing the water. If they will test these certain parameters once a week and keep stuff in check," he explains, "it will cut down the amount of calcium buildup on the tile dramatically — by upwards of 90%.
"Typically we will start with showing them how to test chlorine and pH. Then the next week we will send them an email where we show them how to test for alkalinity. You've got to build on these things slowly, because when you throw everything at them at the same time, their eyes just glaze over, and they aren't going to do any of it."
In the course of these little lessons, most homeowners begin to see that keeping the water balanced is not only doable but can even be enjoyable. And like Cashman does, they see that learning how to handle creeping mineral and metal deposits is an ongoing process with an array of remedies, none of which is a perfect solution in itself. (Of course, the pool-owning math and science geeks working at nearby Los Alamos and Sardinia National Labs are more likely to get into this than the average person, but it's not difficult even for the mathematically impaired.)
Cashman uses an LSI wheel like this one from Taylor to quickly calculate water balance, and in regard to scale, its tendency to either dissolve or deposit calcium. 'Our first week of having a new employee, they will know exactly what LSI is, and that'll tell them what a balanced pool is,' he says.
Cashman is a big fan of using the Langelier Saturation Index to bring pools into balance because it allows users to focus on isolating and adjusting individual factors instead of monkeying with several at once, which can stymie balancing efforts by introducing too many variables.
Most good commercial test kits include an LSI wheel that helps users with this. Cashman uses one from a Taylor kit.
"It takes in a lot of different factors, from the temperature of the water, the pH of the water, the calcium hardness," he says. "What you do is you test your water, and find out where the pH is. You measure the temperature, you find the calcium hardness and total alkalinity, and you line all of those up on a little wheel, and it will tell you where you want to be, which is ideally 0.0. But it is rare that that ever happens. Usually we're at a -1 or -2 or a +1 or +2. You can also get a free app on your phone to calculate this out, but I've done it forever with the wheel and that's easiest for me. Most professional test kits include them."
Let's say the LSI reading is -3, which would make the water "aggressive" and damage walls and grout in search of calcium, or +5, providing the conditions for excessive scaling. With the wheel or the app, you can figure out the easiest way to get the number into the acceptable range. "So if I raised my total alkalinity a little bit, what would it change my LSI reading to?" he says. "And you can just move it, and it'll tell you. Or you can decide you want to adjust the pH a little bit higher or lower and where would the LSI be then? The same with temperature. Pools that run at a higher temperature, like therapy pools running above 90, LSI is extremely important because staining and calcium buildup are a real problem in those pools. Our first week of having a new employee, they will know exactly what LSI is, and that'll tell them what a balanced pool is. Once customers see us using it, they see how easy it is to figure out how to make adjustments and get close to zero."
AGENTS OF CHANGE
In addition to keeping the water balanced, homeowners and service techs often turn to sequestering or chelating agents to help tackle the pesky calcium problem.
"The strength of those products as used in the pool industry are not enough to see the calcium level going down in a pool, because calcium always rises over time as you add water, and the sun evaporates distilled water and dissolved gases," Hales says. "What they do is tie up some of that calcium and make it filterable. This just slows down the rate of increase and gives you less calcium on the tile because there's less of it available in the water. Eventually, though, the concentration will get up to 1,000 ppm, and you'll have to drain the pool."
In the desert southwest, where Hales and Cashman live and work, source water starts with calcium levels as high as 300 ppm and reaches the impossible-to-balance four-digit mark in about seven or eight years, according to the former. Chelation and sequestration can stretch that out by three or four years, he estimates.
KEEP IT CLEAN
Keeping in mind that calcium evaporite will eventually present itself regardless of the source water or maintenance efforts, there are steps you can take to make it easier to remove if it does become a problem.
Auringer likes to break down the oils and other environmental contaminants that exacerbate the problem by giving the calcium something to latch onto and result in a nasty fusion of scum and calcium. Some may be tempted to use acid for this purpose. This temptation is to be avoided, she says.
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"You can't break that oily surface down with acid — that only makes it worse," she says. "What I found helpful when I was servicing pools was using enzymes to break those down so the calcium can't stick to the tile. Use enzymes for a couple of weeks first, then you can go and address the rest of the problem and go back and clean it up completely.
"Once you've got that oil barrier completely broken down, I would encourage you to try a gel tile cleaner. You'd have to drain the pool down to the bottom of the tile so you don't affect the plaster, because it is an acid. And then you have to put just enough gel so that it stays on that tile line without running down onto the plaster. Then, once you do clean it off, make sure that you brush frequently so that the low-pH substance isn't dripping down onto the wall because it is much heavier than the water, and it will slowly roll down the wall, then possibly do some damage to the plaster."
Hales has an even simpler plan: waxing the walls to create a barrier. The economy option is simple Turtle Wax, and on the more-expensive end there are micro-penetrant sealers that are used commonly in the masonry industry.
"Barrier products can mitigate the problem," he says. "They're usually silicone-based and leave a coat of film that's so thin you can't really see it. The calcium can't bond to the silicone the way it can to the tile glaze. You'll still see a white film on there, but you can almost flick it off with your fingernail because it's not chemically bound to the surface. Running a Scotch Brite pad over it will take care of the problem. I always recommend people use those barrier products."
BLAST-OFF
Sometimes a calcium scale problem grows to the point where the homeowner can no longer handle it by him- or herself, and Scotch Brite pads are not doing the trick anymore. Cashman says at this point you've got two ways of mechanically removing the deposits, and which one he chooses depends on the makeup of the tile. One is bead blasting, which is sort of a gentler sandblast that uses glass beads to gently abrade the surface of the tile, and the other is pumice stone.
"In most cases, tile can be brought back to looking like it did originally," he says. "You just have to be very careful and consider the makeup of the tile. Back in the day when you had solid porcelain tile in blue and green, you could bead blast those and not worry about it. But with some of the materials now that look like slate and have a bit rougher surface, you have to be very careful. Best to start with a little sample and make sure it'll hold up. If it's not looking good, we can turn the pressure down from 3,500 psi to around 2,800 and still get the job done."
Some tiles found in today's pools were never intended for such use, and often when Cashman comes across these he has to tell disappointed clients the only solution is an expensive tile replacement.
Pumice can also be effective and is widely available for consumer purchase at pool stores. But Hales warns that while it will take calcium deposits off of tile, it is also aggressive enough to take a little of the glaze off the tile with it.
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"It gets a little worse each time you do it," he says. "So I'm not really a fan. You can use baking soda, and there are chemicals designed to soften it so it's more easily removed. But with any of these, you need to exercise some caution to make sure you're not damaging the tile so the next time you have to do it it's going to be even harder to remove because you've degraded the tile."
CHALK TALK
With so many factors out of a service technician's hands (source water, a homeowner's willingness to test the water, the tile specified by the builder), it can be tempting to just let it go and blast it or abrade it off when it presents itself. And it will. But Cashman says the efforts he, Hales and Auringer outline do make a noticeable difference.
"Back in the day we would kind of chalk it up to, 'Well, this is just part of it,'" Cashman says. "But as time went on and we got a better understanding of water chemistry, we started to realize if we follow these steps and keep up with it, we don't see those extreme problems."
Besides, Hales says, calcium along the tile line is both inevitable and really just a reminder that the builder picked the right material to finish off the pool.
"That's the whole reason why we put tile on the waterline of the pool," Hales says. "Because it's more maintainable."
