E.C. University - Pool Water Balancing

Pool Water Balancing

“Why do I need to ‘balance’ my pool water when it looks fine?”

Well, the short answer is, if the water isn’t properly balanced, your pool may     not be safe to swim, the pool, and its equipment, won’t last as long, and finally, you’ll be wasting your hard earned money on chemicals that you don’t need!!   The water in your pool has more than likely been in the pool for many, many years and is constantly changing, year round. ‘Anything’ that comes in contact  with your pools water affects its ‘balance’. Continuous filtration and sanitation removes contaminants which keep the water looking clear, but do little to ensure proper water ‘quality’. Balancing is vital to achieving healthy and safe water.   

Pool Water Chemistry

Pool chemicals play essential roles in maintaining the specific levels of compounds that are necessary for balancing your pool water. Pool water balancing is the relationship between different chemical measurements in your pool water. How do you know when your water is out of balance? Other than the visible signs of color change and clarity, EC Pool Supply uses testing reagent (drop) kits, strip tests, and digital or analog meters to measure the level of sanitizer, pH, alkalinity, calcium, stabilizer, metals, dissolved solids, and saturation in your pool water.

Langelier Saturation Index (LSI)

Properly balanced pool water can be described as water that is neither aggressive   nor scale forming. Meaning, that pool water will dissolve and hold minerals until it can’t hold any more, in solution, and as a result becomes saturated. Water which is under-saturated will attempt to saturate itself by dissolving everything in contact with it in order to build up its content. Water which is over-saturated will rid itself of some of its content by dropping minerals out of solution, in the form of scale. The Langelier Saturation Index is a formula used to diagnose whether your pool water is balanced in relation to its saturation of carbonates, bicarbonates, hydroxides (alkalinity), calcium, and other dissolved solids. EC Pool Supply will test your pools chemical make-up along with its Saturation Index.

The LSI formula is :  SI = pH+T(f)+C(f)+A(f)+TDS(f) 
SI   - Saturation Index
pH  - Acid/Alkaline Balance
T(f) - Temperature Factor                                  
C(f) - Calcium Hardness Factor  
A(f) - Alkalinity Factor  
TDS(f) – Total Dissolved Solids  

Water Testing

Testing your pool water weekly by bringing a filled sample bottle to your EC Pool Supply store, will help to ensure adequate water balance, an optimum swim environment and a long life for your pool. All water samples should be at least 8 oz. taken from the deep end of your pool at about elbow length for the best sample. We use a variety of testing methods, including Taylor drop kits, 7in1 strip tests, along with phosphates and salt level testers. Testing once a week will keep your adjustments small and it will be easier to maintain the proper chemical levels.

Balancing pH

Balancing pH is important because small changes to the pH will make a large change to the water balance of your pool. When the pH is too low the water will be clear but corrosive. On the other hand when the pH is too high the water will get cloudy and scale will be more likely to form on the finish and tile. The ideal pH level for your pool is 7.4-7.6. This is the best range for swimmer comfort.


Maintaining the alkalinity level in the pool water will keep the pH level from bouncing up and down. If the alkalinity level is too low the pH will move from up to down very easily. When the alkalinity level is too high the pH will stay high and this will make the sanitizer in your pool water less effective. The ideal alkalinity level is between 80ppm-120ppm.

Calcium Hardness

Keeping your calcium in balance will help extend the life of your pool finish. Then main factor in a long lasting pool finish is calcium level. If you have a lower calcium level the easiest thing to do is add calcium hardness increaser. When waters calcium level is low the water will try to take the calcium from your pools finish. If the calcium level is too high the water will release the calcium in the form of scale. The only way to lower calcium is to perform a partial drain and replace with fresh water. Ask your local     EC Pool Supply store for a recommendation on how much water to remove. The ideal range for calcium hardness is 250ppm – 400ppm.

Bringing a water sample to your nearest EC Pool Supply location each week will take the guesswork out of balancing and maintaining clear and safe pool water. We will recommend the chemicals that you need and ‘only what you need’. Stop “thinking” and trust the experts at EC Pool Supply to care for all of your pool needs.