on Calcium Hardness
When it comes to maintaining clean, safe, and crystal-clear water in your hot tub, calcium hardness is an essential part of water chemistry that’s often overlooked. Too little or too much calcium in your hot tub water can wreak havoc on your equipment, surfaces, and even the overall water quality. In this post, we’ll explain everything you need to know about calcium hardness, how it interacts with saltwater systems, and the best products to keep your hot tub balanced.
What is Calcium Hardness?
Calcium hardness refers to the concentration of calcium and other minerals dissolved in your hot tub water. It's measured in parts per million (ppm), and maintaining it within the ideal range is critical to prevent problems like corrosion or scaling.
Ideal Calcium Hardness Range for Hot Tubs
150–250 ppm: This is the sweet spot for most hot tubs. Staying closer to 150ppm is preferred.
Water with too little calcium = soft water
Water with too much calcium = hard water
Why is Calcium Hardness Important?
Too Low Calcium Hardness (Soft Water)
Corrosion: Soft water will try to "steal" calcium from your hot tub’s surfaces, equipment, and plumbing. This can damage your shell, heater, and pumps. This isn’t a huge factor, but combined with an acidic pH, it can shorten the lifespan of you hot tubs components, gaskets, and shell.
Foaming: Soft water is more prone to foaming, which can make your hot tub less enjoyable and more difficult to clean.
Too High Calcium Hardness (Hard Water)
Scale Buildup: Hard water causes calcium deposits (scale) to form on jets, pipes, and heaters. This reduces efficiency and can lead to clogs.
Cloudy Water: Excess calcium often makes the water appear cloudy or milky, no matter how well you sanitize.
Skin Irritation: Hard water can feel harsh and leave a film on your skin.
How Water Softeners Impact Calcium Hardness
Water softeners can be a valuable tool for managing calcium hardness, especially if your water source is too hard. Softened water removes excess minerals, including calcium, which prevents scaling. However, if you fill your hot tub entirely with softened water, you may end up with calcium levels that are too low, leading to corrosion.
Key Tips for Water Softener Users:
Use a Water Softener When Water is Extremely Hard: If your source water has a calcium hardness above 300 ppm, filling with softened water makes sense to avoid scaling.
Balance After Filling: Always test your calcium hardness after filling and, if necessary, add a calcium hardness increaser to bring levels into the ideal range (150–250 ppm).
How to Adjust Calcium Hardness
If Calcium Hardness is Too Low (Soft Water):
Add a Calcium Hardness Increaser:
Products like Leisure Time Calcium Booster are designed to safely increase calcium levels.
👉 Buy on Amazon Disclaimer: As an Amazon Associate, I earn from qualifying purchases.Follow the manufacturer’s instructions for dosage based on your hot tub size (e.g., 2 oz. typically raises calcium by 10 ppm in a 350-gallon tub).
Circulate the water for at least 30 minutes and retest.
If Calcium Hardness is Too High (Hard Water):
Use a Water Softener for Hard Water:
If your source water’s calcium hardness is above 300 ppm, fill your hot tub using a water softener like the Camco TastePURE Portable Water Softener.
👉 Buy on Amazon Disclaimer: As an Amazon Associate, I earn from qualifying purchases.
After filling, test calcium hardness and use a calcium hardness increaser if levels drop below 150 ppm.
Add a Scale and Stain Control Product:
Products like SpaGuard Stain and Scale Control can prevent calcium from depositing on your jets, heater, and other components.
👉 Buy on Amazon Disclaimer: As an Amazon Associate, I earn from qualifying purchases.
Dilute with Softened Water:
If you’ve already filled with hard water and the calcium hardness is too high, partially drain the tub and refill with softened water.
Install a Hose Pre-Filter:
A hose pre-filter can reduce calcium levels during the filling process.
👉 Buy on Amazon Disclaimer: As an Amazon Associate, I earn from qualifying purchases.
Conclusion
Calcium hardness is a key part of hot tub water care that protects your equipment, enhances your soaking experience, and ensures long-term durability—especially if you’re using a saltwater system. By starting with balanced water and following the tips above, you’ll avoid issues like scaling, cloudy water, or corrosion.
