Water Balance

Water Balance

Water wants to be in balance, and it won't take NO for an answer. Water is at balance when it has just the right amount of calcium and total dissolved solids (TDS) in solution. If it has too much, water will release the excess causing ugly and equipment-clogging scale. If there is not enough calcium and TDS, water will pull it from plaster walls (called etching) or from the protective linings of muncipal water pipes.  

A well balanced pool is the easiest stain prevention step you can take.


Langelier Saturation Index (LSI)

The  LSI is an approximate indicator of the degree of saturation of calcium carbonate in water. Simply, it is a great way to see if you water is in balance.

LSI is calculated using:

  • pH 
  • Total Alkalinity (TA)  
  • Calcium Hardness (CH) 
  • Total Dissolved Solids (TDS)      
  • Water Temperature in F
                                                                               

UNDERSTANDING RESULTS

LSI below 0:  Water is in need of calcium. Water will pull calcium and TDS from pool walls, pipes or any other available source.

LSI equals 0:  Water is in balance or neutral.

LSI above 0: Water will give up its extra calcium by depositing scale on pool surfaces and equipment.

Step 1. pH

  • Test the pool water with fresh pool pH test strips or calibrated pH meter
  • Record your pH

Step 2. Temperature F

Measure the temperature (T) of your pool water and record the associated Temperature Factor

  • T - Factor
  • 32 - 0.0
  • 37 - 0.1
  • 46 - 0.2
  • 53 - 0.3
  • 60 - 0.4
  • 66 - 0.5
  • 76 - 0.6
  • 84 - 0.7
  • 94 - 0.8
  • 105 - 0.9

Step 3. Calcium Hardness

Measure the ppms of calcium hardness (CH) of your pool water and record the associated Calcium Hardness Factor

  • CH - Factor
  • 5 - 0.3
  • 25 - 1.0
  • 50 - 1.3
  • 75 - 1.5
  • 100 - 1.6
  • 150 - 1.8
  • 200 - 1.9
  • 300 - 2.1
  • 400 - 2.2
  • 800 - 2.5

Step 4. Total Alkalinity

Measure the ppms of total alkalinity (TA) of your pool water and record the associated Total Alkalinity Factor

  • TA - Factor
  • 5 - 0.7
  • 25 - 1.4
  • 50 - 1.7
  • 75 - 1.9
  • 100 - 2.0
  • 150 - 2.2
  • 200 - 2.3
  • 300 - 2.5
  • 500 - 2.6
  • 800 - 2.9

Step 5. Total Dissolved Solids

Measure the ppms of total dissolved solids (TDS) of your pool water and record the associated Total Dissolved Solids Factor

  • TDS - Factor
  • Below 1,100 - 12.1
  • 1,100 & Above - 12.2

Step 6. Time to Calculate

(pH) + (Temperature Factor) + (Calcium Hardness Factor) + (Total Alkalinity Factor) - (Total Dissolved Solids Factor)

Example (Factor in Bold):

  • pH - 7.3
  • Temp - 78 (0.6)
  • Calcium Hardness - 300 (2.1)
  • Total Alkalinity - 150 (2.2)
  • Total Dissolved Solids - 1,500 (12.2)

Calculation:

[ 7.3 + 0.6 + 2.1 + 2.2 ] - [ 12.2 ] = 0.0 LSI