Testing Your Water

Water Testing and Analysis

Test the water in your pool two to three times a week to ensure an optimum swim environment and a long life for your pool. For the best sample of water, collect from the deep end of the pool - collecting at least eight ounces of water. You can collect the water in a sample bottle or any clean, plastic container. 

Langelier Saturation Index (LSI) Calculator (Scale vs. Corrosion)

The Langelier Saturation Index (LSI) is a way to evaluate your water quality data to determine if your pool or hot tub water has a tendency to form a chemical scale. You need to measure pH, conductivity, total dissolved solids, alkalinity and total hardness to use this index.

Checking Langelier Saturation Index (LSI)

Total Alkalinity ppm
Calcium Hardness ppm
Cyanuric Acid
Temperature (°F)
Measured pH
Salt Pool?
        Your LSI is:

In swimming pool maintenance, the ideal range for the Langelier stability index is -0.5 to +0.5. If your results are below -0.5, your pool or hot tub water is considered corrosive. You will then need to take the required steps to adjust your pH, total alkalinity or calcium hardness. If your calculated results are higher than +0.5, this is an indication that your pool or hot tub water is scale forming. Take the necessary steps to adjust the balancing factors of your swimming pool chemistry.

Testing Ranges

pH    7.2 – 7.6
Total Alkalinity   120-150 parts per million
Calcium Hardness   200-250 parts per million (Concrete Pools)
Calcium Hardness   175-225 parts per million (Vinyl Pools)
Free Chlorine   1-3 parts per million
Free Bromine   3-5 parts per million
Metals: Copper   0 parts per million
Metals: Iron   0 parts per million

The most important factor to your water balance is the pH. The pH sets the tone for your water and keeps it clear and inviting.

Total Alkalinity

Total Alkalinity (TA), refers to the alkaline materials dissolved in the pool water. Your water’s ability to resist pH changes depends on the alkaline material. Low TA can cause the pH to vary in and out of range. High TA makes it difficult to adjust the pH as needed.

Calcium Hardness

Calcium hardness is the amount of dissolved minerals (mostly calcium carbonate) in your water. Low Calcium Hardness can corrode equipment or etch a plaster finish. High levels can lead to cloudy water or scaling. Be sure to bring a water sample to your pool professional. They can analyze the water and provide you with the necessary instruction to ensure proper water balance and chlorination levels in your pool.  Information from regalchemicals.com