What if range chemistry is the wrong thing to focus on when managing water? What if the ranges do not always apply, like in the winter? Theoretically, the textbook ranges for chemistry are ideal. But in reality, that's not always the case. In this article we will explain why we prioritize the Langelier Saturation Index (LSI) first, and range chemistry after that.
LSI is always relevant
In recreational water, range chemistry refers to the textbook ranges for water chemistry. For example, "pH should be between 7.2 - 7.8, and ideally 7.4 - 7.6." The ranges are helpful for pool operators and owners to gauge how good their water chemistry is. We are not questioning the value of range chemistry...we are simply questioning its importance when circumstances change, and perfect range chemistry becomes problematic for the LSI. If we have to chose between range chemistry and the LSI, we choose the LSI.
What is the most unstable chemistry in water? What factor changes most frequently? The answer is pH, and pH is very important because it affects virtually all other chemistries in water.
Unfortunately, pH is hard to manage. pH constantly fluctuates in swimming pools, and if we are aiming to keep the pH "in range", we are aiming at a moving target. It's frustrating, to say the least. And yet, it is common practice in the pool business to juggle acid, bicarb, CO2 and soda ash to attempt to control pH. When the pool is in season and swimmers are using it, pH is important because of sanitization...but is it so important if the pool is laying dormant in the winter, under a safety cover?
In our opinion, no.
Neglected Factors of the LSI
The LSI has six factors:
- carbonate alkalinity
- calcium hardness
- water temperature
- Total Dissolved Solids (TDS, including salt)
- cyanuric acid (CYA).
Do you measure ALL these factors on your pools? If so, how often? They are important factors in the LSI that are very commonly neglected. Play around with our dosing calculator, one factor at a time, and watch the impact they each have on the LSI. You might be shocked.
The habit of many pool professionals is to test chlorine, pH and [hopefully] total alkalinity. We have not met too many people who test water temperature.
Ignored LSI factors still matter!
If you factor in all 6 variables of the LSI, you may discover ways to simplify your job as a pool operator. For example, the calculator teaches us the value of calcium hardness. It anchors the LSI, and it is remarkably stable. This stability is why calcium is the rock we build our pool chemistry strategy upon. And yet, calcium remains so misunderstood and disliked because people think higher levels of calcium hardness is what causes carbonate scale. But in fact, a high LSI is what causes scale formation...not high calcium hardness alone.
The most important example of why LSI matters more than range chemistry occurs in the winter. Water temperature is an important factor on the LSI, and cold water makes water more aggressive. This means winter water chemistry must be managed differently in the winter than in the summer. And in order to maintain LSI balance in the winter, you will have to break out of the textbook ranges with elevated levels of calcium, alkalinity or pH.
Since balancing the LSI may be a challenge for those who have never tried, here is a handy chart that offers some recommended range targets based on water temperature, which should allow you to maintain LSI balance at any temperature. And it also shows different recommendations based on your primary sanitizer.
When we change our mindset from chasing pH, and instead focus on balancing the LSI, the value of calcium becomes undeniable. Calcium may not buffer the pH directly, but it certainly stabilizes the overall LSI. A good LSI balance allows you to more easily contain pH, rather than trying to control it.
Wouldn't it be nice to have a foundation of calcium that gets you closer to equilibrium? What could that do for your water? How could that help your bottom line? Imagine how much less you would need to spend on sodium bicarb, soda ash and acid if your calcium level gets you close to LSI balance? You would be making micro-adjustments to your water chemistry...not major ones. The Orenda App's LSI Calculator taught us this revelation.
Water Craves LSI Balance
Let's take a step back from the chemistry classroom real quick, and put all this message into the real world. We at Orenda have made teaching the LSI a cornerstone of our company's mission. Why? Because it's real. It does matter. For too long, we in this industry have been taught behaviors and habits that work for range chemistry management, but ignore other factors of the LSI. Sure, the quality handbooks in the pool business discuss the LSI and its importance...but it's a tough equation that most people will not do in the field. The economics of managing swimming pools simply do not allow for extended pool visits involving higher math.
That's why we have so heavily invested in our mobile app's LSI calculator. It is a tool so you can calculate the LSI very quickly and easily. AND it tells you how to correct it on your own terms.
We recommend looking at higher levels of calcium hardness in your water so you can see an alternative way of managing your chemistry. See if it works for you. You may find you're spending a lot less money chasing a moving target, and a lot more confidence knowing you are protecting your customer's pool and equipment from winter damage.