How to Increase Calcium in Pools

Calcium hardness levels in swimming pools should be 250 parts per million (ppm) or higher depending on your region and water supply. However, it should never be lower than 150 ppm. If the calcium level is low, swimmers may experience eye and skin irritation, fiberglass pools may blister and plaster pools may become pitted. But you don't want to raise the calcium hardness too high or the pool water can become cloudy and cause scaling on the pool fixtures.

Things You'll Need

• Calcium hardness test strip kit
• Calcium chloride
• Bucket

Instructions

1. Test the water for calcium hardness using one test strip. Dip the strip in the water in the deep end of the pool about 12 inches down in the water or as far as you can reach comfortably. Pull the strip out of the water and compare the color to the test kit color chart. If the calcium hardness level is below 150 ppm, you need to increase the level.

2. Fill a bucket to the top with warm water.

3. Add 2 oz. of calcium chloride per 1,000 gallons of water in the pool to increase the calcium level by 10 ppm. For instance, if you need to raise the calcium hardness level by 40 ppm in a pool with 20,000 gallons of water, you would use 10 lbs. of calcium chloride or 160 oz. of liquid product.

4. Broadcast the solution in the bucket around the deep end of the pool. Start at the beginning of the deep end and walk around to the other side while pouring the solution in the water. Run the filter for six to eight hours to circulate the water.

5. Retest the water with another test strip. Assuming that the level is correct, test the pH and chlorine levels in the water and adjust if necessary.

References

• North Carolina State: Water Chemistry for Swimming Pools
• Pool Calculator: Basic Pool Chemistry
• Pool Manual: Hardness