To add hardness to your pool water, you typically use a chemical called calcium chloride. Maintaining the correct calcium hardness level is essential for pool health and longevity.
Why Calcium Hardness Matters
Calcium hardness refers to the amount of dissolved calcium and magnesium in your pool water. Proper levels help prevent the water from becoming corrosive or scaling.
- Low Hardness: Water with low calcium hardness is "soft" and can become corrosive. This soft water will seek calcium from other sources, potentially damaging pool surfaces, plaster, grout, and even metal components like ladders and heat exchangers.
- High Hardness: Conversely, water that is too hard can lead to scaling, where calcium deposits form on surfaces, equipment, and in pipes. This can reduce circulation and damage filters and heaters.
Maintaining calcium hardness within the recommended range (typically 175-250 parts per million, ppm, for plaster pools and 150-225 ppm for vinyl, fiberglass, or painted pools) is a key part of balancing your pool chemistry.
Calculating the Right Amount of Calcium Chloride
Adding calcium chloride is the standard method to increase calcium hardness. The amount needed depends on your pool's volume and how much you need to raise the ppm level.
A helpful guideline for adding calcium chloride is as follows: use 2 oz. of calcium chloride for every 1,000 gallons of water to raise the ppm by 10.
To calculate the required amount for your specific pool:
- Determine your pool's volume in gallons.
- Test your current calcium hardness level using a reliable test kit.
- Determine your target calcium hardness level (based on pool type).
- Calculate the difference between your target and current levels (how many ppm you need to raise).
- Use the guideline to calculate the total ounces of calcium chloride needed.
Example Calculation
Based on the provided guideline:
If your pool holds 10,000 gallons of water, and you wish to raise the ppm by 20, you must add 40 oz. of calcium chloride to the water.
Here's how this calculation works:
- You need to raise the ppm by 20.
- Raising by 10 ppm requires 2 oz per 1,000 gallons.
- Raising by 20 ppm requires (2 oz / 10 ppm) * 20 ppm = 4 oz per 1,000 gallons.
- For a 10,000-gallon pool, you need (4 oz / 1,000 gallons) * 10,000 gallons = 40 oz.
You can visualize this with a simple relationship:
| Gallons | Desired ppm Increase | Oz of Calcium Chloride |
|---|---|---|
| 1,000 | 10 | 2 |
| 1,000 | 20 | 4 |
| 10,000 | 10 | 20 |
| 10,000 | 20 | 40 |
Note: Always double-check your calculations and consider adding chemicals in smaller increments if unsure.
Steps to Add Calcium Chloride
Once you have calculated the correct amount, follow these steps to safely add calcium chloride to your pool:
- Turn on the pool pump to ensure water circulation.
- Weigh out the calculated amount of calcium chloride using a reliable scale.
- Pre-dissolve the calcium chloride in a bucket of pool water. Never add dry calcium chloride directly to the pool surface, especially in vinyl liner pools, as it can cause damage. Use a clean bucket and stir until dissolved. You may need multiple buckets depending on the amount.
- Slowly pour the dissolved solution into the pool, typically around the perimeter or in front of return jets to help with dispersion.
- Allow the pool pump to run for at least 4-8 hours (or one full circulation cycle) to distribute the chemical evenly.
- Retest the calcium hardness level after 24 hours to ensure the desired level has been reached. If not, repeat the process with adjusted calculations.
Safety Tip: Wear appropriate personal protective equipment (PPE) like gloves and eye protection when handling pool chemicals.
Adding hardness to your pool water is a straightforward process once you understand the calculation and application steps. Regular testing helps maintain balanced water chemistry, protecting your pool and enhancing the swimming experience.
