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Honesty in Water Testing

If you’re not testing, you’re just guessing

Water testing is too often rushed and overlooked in our industry. A few months ago, I had the opportunity to take the start up certification course for the National Plasterer’s Council, hosted by Bel-Aqua. As an employee of Orenda, I work with service techs and plaster companies every week. This course was a wonderful opportunity to soak up information like a sponge, and learn more about the business. Granted, I was not actually supposed to take the course (Orenda was a sponsor of the event, and I am not a service tech), but I was invited to participate.

The certification course is taught by the NPC’s Director of Technical Services, Greg Garrett. Not only did Greg cover a broad range of plaster topics, he covered an even broader range of water chemistry. This article shares a few of my takeaways from the class.

1. Accurate water testing is very important

The key word here is accurate.

Do you do initial water treatments for new or re-plastered swimming pools? If you do the initial water treatment, you know how important it is to get the water balanced as soon as possible. So tell me…how can you balance the water if you do not have accurate chemistry readings to begin with? You cannot dose chemicals correctly–even with a dosing calculator like ours.

2. If your water chemistry exceeds the range of the test kit, say so

This point is the impetus for why I wrote this article. The most impactful moment in the entire startup certification course was when we tested water, and Greg Garrett shared a story of his; a hard lesson learned. The example he gave involved a Taylor test kit for cyanuric acid. The test kit has a black dot at the bottom, and you add the prescribed amount of reagent and water until you can no longer see the dot. If the vial is filled to the top line, the reading is 30 ppm of cyanuric acid. If you can still see the dot, the correct answer is “less than 30 ppm”. Here is good video that walks through the Cyanuric acid test I am describing:

After doing the test, Greg, like so many of us would, indicated “0 ppm”. After all, the sample water was completely clear. But since the test kit only went to 30 ppm, that “0 ppm” was assumed, and unproven. Lesson learned.

I share Greg’s story because it is a painful illustration of the shortcuts we in the industry often make. How many of us have ever hurried through testing water? All of us. How many of us have ‘eyeballed’ the line? Or lost count of the drops? Or never calibrate the reagents in the test kit?

I recently made a similar mistake, but thanks to Greg’s story, I caught myself, went back and corrected it. I tested the pH of some tap water in Seattle, and it was clearly above 8.0 pH. But how far above?  I could not tell with the kit. I am so glad I did not report the 8.5 I originally wrote down.

This article is about honesty in water testing. A dosing calculator like ours depends on accurate, honest water testing by you. Otherwise, it’s garbage in, garbage out.

3. Use a better test kit when necessary

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The basic training manual has a wealth of valuable information in it.

According to the IPSSA Basic Training Manual (pg. 161), phenol red reagent (used for testing pH) only shows pH between 6.8 and 8.0. Any pH below 6.8 will look the same as 6.8 (virtually clear). In other words, if the pH is lower than 6.8, you would never know. That’s why using a different test kit is sometimes necessary.

When we visit customers and go to their pools, we test water. If we do not have the necessary kit(s) for accurate water testing, we collect samples in a clean water bottle, and we take it somewhere with a better kit. You may not need to purchase a high-dollar testing machine, as most local pool stores have one. Simply pay for them to test the water for the factors you need.

What is a good option for those of us with color blindness?

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Many of us struggle with red-green color blindness. Can you clearly see the number in this image? If not, consider an electronic test kit. Colorimeters may not be the best option for you.

There are four types of water testing kits most commonly used in the aquatics business.

  1. Color Comparison (test strips or colorimeter)
  2. Drop Count (titration)
  3. Turbidity (like a cyanuric acid test)
  4. Electronic (like a photometer)

If you are color blind (particularly with red-green), consider an electronic photometer to read the results for you. For commercial pools, electronic probes for ORP, pH and chlorine are strongly recommended. Just find the test kit that works for you.

4. Test the fill water

This is one of our most drilled talking points at Orenda. Knowing what water chemistry comes out of the tap is paramount for success. This is especially true for pools with auto-fill or pools and spas that regularly drain some water to dilute. For example, if your cyanuric acid levels are too high, draining and diluting is often the most reasonable option. To balance the incoming water, you need to know what’s in it. Water testing is the best way to know for sure. Remember, if you’re not testing, you’re just guessing.test fill water

Back to those of us who do initial water treatments for startups…accurate water testing of the fill water is critical to success.

Another way to find out what is in the tap water is to request the test results from the water treatment company. Municipal water treatment plants are required by law to test their water, and it is public information. Just ask, and you shall receive. Tell them what you’re looking for too…don’t just ask for pH, alkalinity and the basics. Get everything you may need, including metals and phosphates.

Water testing is the professional thing to do

Customers depend on you to manage water the right way…just like we expect a carpenter to measure before he cuts, and a plumber to seal every pipe watertight. Accurate, honest water testing is the first step in getting there. Thanks for your time.

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Pool Winterization Water Chemistry

Pool Winterization and Water Temperature

If your climate requires pool winterization, this article is for you. When do you winterize your pool…September? October? Later? More importantly, how do you leave the water chemistry before putting the winter pool cover on? And do you treat the water throughout the winter?

When we ask these questions to the pool service industry, we get a wide range of responses. But overall, it seems like most pool service techs don’t come back until it’s time to remove the winter pool cover and open the pool for the season. At best, this practice is a missed opportunity; at worst, it’s a liability. Pool winterization is something that we as an industry can be much, much better at. If you would like to hear my two cents on the matter, keep reading.

“Just Following Industry Standards”

The question is this: What is the water chemistry that we leave behind after pool winterization? Are we just following industry standards like usual? You know, range chemistry; the same way you would treat the water during the summer season.

As a fellow pool professional–since 1984–I know what I’m about to talk about cuts against the grain. As pool professionals, we have been trained to manage water chemistry by “industry standard ranges”. The goal of this concept is to maximize chlorine efficacy and water clarity; our two top priorities when the pool is open. After all, we’re managing water people submerge themselves in! Of course it needs to be safe from disease, and of course it should look clean and clear.

But where do sanitation and water clarity apply to pool winterization? Are people swimming under the winter pool cover? No. The priority for closed pools should be water balance–based on the saturation index–and then chlorination and water clarity. Just following industry standards after pool winterization is virtually guaranteeing permanent damage to the pool.

RELATED: Cold Water is Corrosive

The relationship between water temperature and sanitizer efficacy

As the water temperature rises, so too does the sanitizer demand. Not only are living organisms more active in warmer temperatures, but most chemical reactions–in pools, anyway–occur faster in warmer water too. Below 55ºF, sanitizer demand is much less than say, 85ºF. I say this from personal experience.

We cannot ignore sanitation below 55º, but let’s be honest. Keeping a pool algae-free in the winter is much easier than in the summer. I’m here to tell you that temperature is a major reason why.

As water temperature declines, so too does the speed of chemical reactions. Take for example an Orenda product like CV-600 enzyme. Enzymes are reactive beginning at approximately 65ºF. Below 65, they slow down and go dormant.  It is also difficult to dissolve chemicals like calcium or sodium bicarb in cold water. Have you ever noticed that?  I have.

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Undissolved calcium thrown into the pool, and the operator left. This photo was taken one week later.

So let’s take water temperature into primary consideration for pool winterization. We should always pre-dissolve and circulate dry chemicals when the water is still warm enough to do so. If you need to add calcium or bicarb to prepare your water’s LSI for pool winterization, do so weeks before closing when the water is warmer. Ensure full mixing occurs and no undissolved material stays on the pool floor. Calcium, for example, can damage a pool surface if left on it directly for extended periods of time.

Phosphate removal, enzymes and sequestration works better in warmer water

I suggest that phosphate treatments occur weeks before pool winterization for two reasons. First and foremost, give the reaction time to complete, and clean up the precipitate. Secondly, related to temperature above, the reaction will be slower in cold water.

The same goes for using SC-1000 or any other type of sequest or chelant. It is a common industry practice to add sequest during pool winterization. I question this practice due to water temperature. In our experience, SC-1000 is better applied in the spring during pool openings rather than pool winterization.

Industry standard ranges should take a back seat to LSI balance during pool winterization

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Look at the difference water temperature makes on the LSI…

When you use the Orenda LSI Calculator, adjust the temperature dial down to winter temperatures. You should notice a problem. See how the LSI goes down? The same “industry standard” water chemistry ranges will not protect your pool in the winter. In fact, it virtually guarantees severe surface damage over time…regardless of what type of pool you have. Water is relentless in its demand for equilibrium.

Since we have established that water temperature is such a critical factor in the LSI…why are we closing pools in September?

Pool winterization can wait a few more weeks

In some cases, October can have nice, warm weather. Yes, even in the American Northeast and Midwest. Perhaps a strategy to consider would be to postpone pool winterization until late October. This does a few things…

  • Allows for a longer season of pool use and enjoyment
  • Lower closing temperatures (less chemicals required to adjust for the upcoming winter)
  • Increased revenue for pool service companies

If we are just a bit more patient with pool closings, the water will be closer to its winter temperature. If you wait too long, the water will be too cold (as discussed in detail above), but find a time that works for you. Stretch that season a few more weeks, and I believe it will benefit the customer and your service company.


Calcium Crystals: an extreme example of etching that proves my point

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Hardened calcium crystals chipped off a plaster pool surface. Where do you think the calcium came from?

We have come to witness a big problem in colder climates: calcium crystals. These crystals form on cement surfaces like plaster and tile grout. So many people thought this was scale, but in fact, it’s the opposite problem of scale. These crystals form in very low LSI, cold water. These calcium crystals are an extreme form of etching…you can literally see how much calcium has been extracted from your pool surface or grout. Treating them with acid is the exact opposite of what should be done, because it lowers the LSI further.

Fortunately, we have had tremendous success in solving this problem.

  1. Balance the LSI of the water
  2. Purge the pool with 32oz of SC-1000 per 10,000 gallons of water. SC-1000’s 10.8 pH does not lower the LSI, it actually helps raise it.
  3. Continue using SC-1000 weekly and maintaining LSI balanced water until the crystals are gone.

More meaningful pool care through simplified best practices

Preventative care beats repetitive repair.

Add calcium if your pools suffer this crystalline problem. If you have these calcium crystals, it means your water is hungry for calcium and low on the LSI. We recommend 400ppm calcium to give you some grace. After all, it makes more sense to adjust constant factors (like calcium) before fluctuating ones (like pH).

In conclusion…

  • Consider extending the pool season into October if you can. It gives the pool more time to be used, and less time to be closed. It improves pool ownership value and can increase service company revenue too.
  • Cold water is the factor we have to adjust for in pool winterization. It slows chemistry, lowers sanitizer demand, and most importantly, lowers the LSI.
  • Remove phosphates at least a week before pool winterization so you have time to come back and vacuum, and clean the filter.
  • Purge with CV-600 when the water is still above 65ºF. It is very helpful to do a deep clean of the inside of the pipes before clearing the lines and lowering the water level.
  • Do not over-chlorinate at the end of the season. 3-5ppm should be plenty, as the sanitizer demand is only decreasing as the temperature drops. Besides, nobody is swimming under the pool cover.
  • If you winterize pools, we recommend 400ppm calcium. Use the Orenda LSI calculator to manage it. You will find it’s a valuable ally, especially in the winter.

For more information or specific questions, contact us.  Thank you for your time.

Entendiendo el ISL, Orenda, ISL, químicos piscina,

Entendiendo el ISL: Índice de Saturación Langelier


Entendiendo el ISL: Índice de Saturación Langelier

Entendiendo el ISL: El Índice de Saturación de Langelier es una fórmula que fue desarrollada a partir de estudios conducidos por el Dr. Wilfred Langelier a principios del siglo veinte. El ISL funciona como sistema base para balancear el agua y los niveles de saturación, en este artículo intentaremos proporcionar una explicación breve y sencilla sobre su funcionamiento. Aunque dicha información puede ser ciencia compleja, será de gran ayuda para cualquier dueño u operador de albercas.

Piense en el ISL como una herramienta de apoyo

Entendiendo el ISL, ISL calculadora, calculadora de OrendaUn nivel perfecto en la escala del ISL es igual a cero (0.0). Cero es un nivel de agua perfectamente balanceada, con el nivel correcto de saturación, calcio y sólidos disueltos, asì como un nivel de pH estable. Debido a que el agua es el solvente universal, si se encuentra desbalanceada, buscará encontrar su propio balance y equilibrio para llegar a un nivel del ISL igual a 0.0; por ejemplo: si no tiene suficiente calcio, el agua se disolverá y extraerá el calcio del yeso en las paredes de la alberca. (Aguafuerte)

El índice de saturación de Langelier es básicamente una manera de determinar si el agua es corrosiva (ISL negativo) ò si es propensa a formar sarro (ISL positivo). Un valor del ISL entre -0.3 y +0.3 se encuentra en un rango aceptable, sin embargo, el valor ideal siempre será 0.0.


La palabra clave es saturación, un nivel ideal de saturación en el ISL es 0.0. El agua busca estar en equilibrio de manera natural, y buscarà la manera de estarlo. Un nivel de saturación insuficiente, es corrosivo, mientras que el agua sobresaturada formará sarro. El agua tiene un límite en cuanto al nivel de calcio que puede mantener en suspensión, una vez que el agua está en el nivel de saturación correcto, dejará de engravar marcas en la piscina. En este caso, nuestra tarea como profesionales en mantenimiento de albercas, nuestra meta es balancear el agua de manera adecuada (así como mantener dicho balance) de manera que no se produzcan ni sarro ni marcas en las paredes de yeso.

Un nivel bajo en el ISL no sólo corroe el yeso, también es corrosivo para los aditamentos de su piscina. Esta es una de las razones por las cuales es de gran importancia utilizar aisladores de metal en las piscinas, especialmente durante el acondicionamiento inicial.

Así como el calcio, el agua disuelve metales y los mantiene en suspensión, hasta sobre saturarse; entonces los metales (comúnmente restos de bronce, aluminio o magnesio de productos para albercas como algicidas) producirán manchas en las superficies de la piscina. Un producto de aislamiento efectivo, como el SC-1000 puede prevenir que dichas manchas ocurran.

Còmo calcular el ISL: una ecuación con seis variables

Las seis variables necesarias para calcular el Índice de Saturación de Langelier son:

  • pH
  • Temperatura
  • Concentración del calcio (ppm)
  • Alcalinidad (ppm)
  • Ácido Cianúrico/Estabilizador (en caso de ser aplicable, corrección basada en el pH)
  • Sólidos Disueltos Totales (ppm)

Dichas variables están relacionadas con factores numéricos equivalentes, asignados en la Tabla Numérica de Equivalencias de Langelier. Mira la tabla siguiente:

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La Ecuación del ISL

(pH) + (Temperatura ºF) + (Concentración del Calcio) + {(Alcalinidad Total) – (ACy factor de corrección @ pH actual)} – (SDT) = ISL

Veamos el siguiente ejemplo. Se encarga de una piscina con los siguientes niveles químicos:

  • pH: (7.4)
  • Temperatura: 84ºF (0.7)
  • Concentración del calcio: 300 (2.1)
  • Alcalinidad: 100 (2.0)
  • Ácido Cianúrico/Estabilizador: (Sì, @ pH 7.4 = 0.31)
  • Sólidos Disueltos Totales < 1000 (12.1)

Hagamos el cálculo.

(7.4) + (0.7) + (2.1) + [(2.0)-(0.31)] – (12.1) = X ISL

[(10.2) + (1.69)] – (12.1) = X ISL

[11.89] – (12.1) = -0.21 ISL

Màs sobre los factores del ISL

  • pH: Esta variable es la más propensa a elevar o disminuir sus valores, como la mayoría de los operadores de albercas ya saben. En el cálculo del ISL, no tiene factor, solo el valor mismo del pH (por ejemplo: 7.2). Entre más bajo el pH, más ácido; y entre más alto sea el valor del pH, será más alcalino.
  • Temperatura (ºF): La temperatura afecta la velocidad de las reacciones químicas en el agua. Entre más baja sea la temperatura, más fácil será que se presenten reacciones corrosivas. Entre más alta sea la temperatura, el calcio  será más propenso a suspenderse. Esto explica porque las celdas de calcio comúnmente tienen carbonato de calcio en ellas.
  • Concentración del Calcio: Esta es una medida de cuánto calcio se encuentra disuelto en el agua. El agua que se encuentra sobresaturada con calcio es más propensa a formar sarro, pero solo si el pH y el nivel de alcalinidad total permiten que salga de la solución. La concentración del calcio-al igual que la alcalinidad total-funcionan como regulador para el pH.
  • Alcalinidad: En la fórmula original del Índice de Saturación Langelier, el Dr. Langelier utilizó la concentración alcalina. Sin embargo, con el tiempo, se volvió evidente que los niveles químicos del agua para piscinas de nado es diferente que el de cualquier otro tipo de agua, es por eso que resulta más preciso utilizar alcalinidad de carbonato. La razón para este cambio es que muchas albercas usan ácido cianúrico como estabilizador. Debido a esto, la alcalinidad requiere de una corrección matemática cuando el CYA está involucrado. Puedes encontrar más información en el esquema siguiente.  Además el sarro es prácticamente carbonato de calcio, así que cuando miramos qué tipo de alcalinidad (carbonato, bicarbonato o hidróxido) medir, la alcalinidad de carbonato es la que se encuentra en mayor relación directa a la formación de sarro.
  • Ácido Cianúrico: Si el CYA se encuentra presente, ajuste la alcalinidad total con el factor de corrección cianurìca en el esquema siguiente para encontrar el factor de carbonato alcalino. El factor de corrección del CYA es aproximadamente ⅓, si se redondea. Para encontrar un nivel exacto, debe conocer el pH del agua y seguir el esquema.
  • Sólidos Disueltos Totales: SDT es la medida de todo lo que se encuentra disuelto en el agua, flotando en suspensión. Se mide en partes-por-millón. y puede incluir desde calcio y metales hasta otros químicos. Comúnmente, los cálculos del ISL asumen menos de 1000 ppm o más. Para encontrar un nivel exacto, siga el esquema siguiente.

Cosas que el Índice de Saturación de Langelier nos enseña

Si miramos a la tabla de valores, notaremos que la concentración del calcio y la alcalinidad total tienen un impacto similar en el ISL. Esto es importante porque significa que la alcalinidad total no es la única con el poder de estabilizar el pH. La concentración del calcio también puede estabilizar el pH.

Además el ISL ofrece un panorama distinto sobre la química en el agua. Entendiendo que tan saturada se encuentra el agua con metales y calcio, es posible predecir posibles daños en el yeso, y prevenirlos. Por otra parte, si el ISL es positivo, el agua será propensa a formar sarro, incluso si no es visible. Así que como profesionales o dueños de albercas, el ISL ofrece un amplio panorama sobre la química del agua, que va más allá del pH y los niveles de cloro.

En Orenda creemos que dos medidas–ISL y ORP–serán las medidas estándar en el futuro para el mantenimiento de piscinas.