To get calcium out of pool water, the most effective and permanent method is to partially drain the pool and refill it with fresh water.
Understanding Pool Water Hardness
Calcium hardness (CH) refers to the total amount of dissolved calcium and magnesium minerals in your pool water. While some hardness is necessary to prevent corrosion of pool surfaces and equipment, too much calcium can cause problems.
High calcium hardness can lead to:
- Scaling: White, crusty deposits forming on pool surfaces, tiles, and equipment.
- Cloudy Water: Excess minerals can make the water appear hazy.
- Reduced Equipment Efficiency: Scale buildup can clog filters, heaters, and salt chlorine generators.
- Rough Surfaces: Plaster or grout can feel rough due to calcium deposits.
Maintaining calcium hardness within the recommended range (typically 200-400 parts per million, or ppm, depending on the pool type and finish) is crucial for pool health and longevity.
The Most Effective Method: Partial Drain and Refill
Unlike many pool chemistry issues that can be adjusted with chemicals, significantly reducing calcium hardness is primarily a physical process. Adding chemicals that lower calcium typically isn't practical or effective for large volumes of pool water.
According to experts, to reduce calcium hardness permanently is best to partially drain the pool water and refill it. This process removes high-calcium water and replaces it with low calcium tap water. This is the most reliable way to lower your pool's calcium hardness level over time.
How Partial Draining and Refilling Works
This method is effective because you are physically removing water with a high concentration of dissolved calcium and replacing it with water that has a lower concentration (your tap or fill water). The extent to which you lower the calcium hardness depends on how much water you drain and the calcium level of your refill water.
Steps for Partial Draining and Refilling
Here’s a general outline of the process:
- Test Your Water: Before starting, test your pool water to determine the current calcium hardness level. Also, test your tap or source water to know its calcium hardness. This helps you estimate how much water needs to be replaced.
- Lower the Water Level: Using a submersible pump or your pool's drain setting (if applicable and safe for your pump), partially drain the pool water. Draining 1/3 to 1/2 of the water is a common practice, but the exact amount depends on your starting CH and desired level. Do not drain vinyl liner pools excessively, as the liner can shrink or shift. Be aware of the local water restrictions and potential impact on the water table if draining a large volume.
- Refill the Pool: Fill the pool back up to its normal operating level using fresh water with lower calcium content.
- Re-Test Your Water: Once the pool is refilled and the water has circulated thoroughly (run the pump for several hours), re-test the calcium hardness.
- Repeat if Necessary: If the calcium hardness is still too high, you may need to repeat the partial drain and refill process.
Why This Method is Permanent
The key advantage of draining and refilling is that it removes the calcium minerals from the pool. Chemical treatments that might "soften" water often involve complex reactions that aren't suitable or sustainable for pool volumes. Therefore, physically replacing the water remains the go-to solution for a lasting reduction in calcium hardness.
By implementing a partial drain and refill, you can effectively manage high calcium hardness and protect your pool investment.
