Water Balance

Water Balance

When water has just the right amount of calcium a in solution in a particular environment, life is good.  Water looks good, surfaces free from problems.   If water has too much of a good thing, then water will release the excess calcium causing ugly surface issues and equipment degrading scale. If the water is lacking what it needs, the water will pull it from whatever it can to satisfy what it craves - metals, typically in the form of calcium. 

A well-balanced pool is the easiest way to prevent common (and uncommon) pool headaches.


A well-balanced pool consists of these "Water Balance" factors and ranges:

  • pH 
    • Ideal 7.4-7.6 ppm &  Acceptable 7.2-7.8 ppm
  • Total Alkalinity (TA)  
    • Ideal 80-120 ppm &  Acceptable 60-180 ppm
  • Calcium Hardness (CH)   
    • Ideal 200-400 ppm &  Acceptable 150-1,000 ppm
  • Total Dissolved Solids (TDS)  
    • < 1,500 ppm 
  • Water Temperature

When these factors are in an ideal range, their function will be good.  Good for you.  Good for pool.    Mostly.

Often clumped together in "Water Balance" are all the other things that can and are often testing in pool water.  Those these are important to water care, they do not explicitly alter "water balance".   Examples of these are chlorine, iron, copper, stabilizer, borate, ORP, etc, etc.



Each one of the previously shown water balance factors have their own individual ideal levels or ranges.   It is important to maintain these at those levels for their own individual reason.  However, when you look at these factors collectivly, even if those factors you can control are smack in the middle of ideal ranges, the factors you cannot control can disrupt the whole "water balance".   

A long time ago some really smart guy created the saturation index.  This index, now fully adopted by the pool industry, is used as an indicator of waters ability to dissolve or deposit calcium carbonate, and is often used as an indicator of the corrosivity of water.   In other words, when calculated out - the index (sometimes referred to as LSI) tells us if the water will form scale or if the water is corrosive.   Unfortunately, it is a lil' complicated to explain how the ranges translate to a nice neat number - but our calculator can do the work for all of us.                                         

Using the calculator below - The number provided gives an indication value of the water quality or "water balance".

LSI below -0.3 (negitive):  Water is corrosive.  Water is in need of calcium.  Water will pull hardness from anything it can touch including pool surfaces, pipes or any other available source.

LSI equals -0.3 to 0.3:  Water is in the balanced range. ZERO = PERFECT!

LSI above 0.3 (positive): Water is scale forming.  Water will give up its extra calcium by depositing scale on pool surfaces and equipment.



There is not much any of us can do about temperature.   This water balance factor will dictate, especially for those in Northern States, how to actually balance the water.    Typically the colder the water, it can be offset with more calcium in the water.   In the event of too much calcium - unfortunalty the only reliable way to combat that is dilluting water with new water with less calcium and maintain a lower pH and total alkalinity.  When that is not practical, all you can do is fine tune the other water balance factors.   Additionally you can extend the LSI by using a chelating agent like Stain Drop All Purpose XpH.

As for Total Dissolved Solids (TDS), homeowners don't have this test ability.  Testing supplies for this are a little pricy.   If you want to know, most pool stores should be able to test it out.  Ultimatly, if you are using a traditional sanitizer like chlorine and the water is fairly new, then you can assume the TDS is below 1,000 ppm.   If the water is older and runs a heavier calcium level, then you can assume above 1,000 ppm.  TDS is a minor adjustment to the Index/LSI number.  Good to know, but its ability to push the needle is minimal.

Calculate Your LSI

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