How to Measure the Hardness of Pool Water

Pool maintenance will often require you to take weekly measurements of chemicals in your pool water. Another reason to test the pool water is to measure the "hardness" of the water. Hard water in your pool can result in a buildup of calcium scales in your pool. Calcium scales can result in buildups that restrict water flow through pipes going into and out of the water filter. If this occurs you need to take corrective actions to prevent permanent damage to your pool or the filter.

Things You'll Need

• Water test kit
• Water softener
• Alkalinity increaser
• Alkalinity decreaser
• pH increaser
• pH decreaser

Instructions

1. Test the pool water for hardness. Purchase a test kit from a reputable pool supplier. Follow the manufacturer's directions for testing the water.

2. Compare your pool water test results to the chart included in the test kit. In many tests, a color-coded chart will indicate the calcium hardness in your pool water, along with other chemicals in your pool. Proper calcium hardness levels should be from 200 to 400ppm (parts per million).

3. Correct high calcium hardness by draining some water out of the pool and adding softer water as a replacement. To drain the pool, turn the valve on the pool pump to filter or backwash and run the filter for several minutes. Add water by running it through a water softener before allowing it to enter the pool.

4. Adjust alkalinity to correct low calcium hardness in pools. Alkalinity increaser or decreaser will ensure correct levels in your pool water, which should range from 80 to 100ppm.

5. Maintain proper pH levels for low calcium hardness. Add pH increaser or decreaser to ensure the pH level in your pool is from 7.2 to 7.8 at all times.

Tips & Warnings

• Never mix chemicals prior to adding them to your pool.

• Always follow the manufacturer's instruction when using pool chemicals.

References

• "Swimming Pool Maintenance"; National Institute of Technology; Tiruchirappalli; n.d.