Calcium Hardness in Hot Tub Water: What It Is and How to Manage It

Maintaining the right water balance in your hot tub is essential for a comfortable and enjoyable experience. One key factor to monitor is calcium hardness, which plays an important role in your hot tub’s water chemistry. If the calcium hardness level is too high or too low, it can lead to problems that affect the water’s clarity, your equipment’s longevity, and your bathing experience. In this post, we’ll explain what calcium hardness is, why it matters, and how to manage it effectively.

What is Calcium Hardness?

Calcium hardness refers to the amount of dissolved calcium in your hot tub water. Calcium is a natural mineral found in water sources, and its presence helps maintain the proper balance of minerals in your hot tub water. If the level of hardness is too low or too high, it can cause several issues for both the water quality and the equipment.

Hardness is measured in parts per million (ppm). The recommended level for hot tub water is typically between 150-250 ppm, although this can vary depending on the specific brand of hot tub. To maintain balanced water, you should test the hardness level regularly and adjust it as needed.

Why Does Hardness Matter?

Calcium hardness is crucial because it directly impacts both the water quality and the condition of your hot tub’s equipment. Here are the main reasons why it’s important to keep calcium hardness levels within the proper range:

1. 1. Water Clarity and Comfort
      
      • • If hardness levels are too low, the water may become corrosive, leading to the degradation of the hot tub’s surface, plumbing, and equipment. This can result in cloudy or discolored water, which may be uncomfortable for soaking.
      • • If hardness levels are too high, the water may become cloudy due to excess minerals in the water. The water may also leave mineral deposits on the hot tub surfaces, making it look unclean and reducing water clarity.

1. 1. Protecting Equipment
      
      • • Low hardness can cause the water to become corrosive, which can damage the hot tub’s heater, pump, and plumbing. Over time, this may result in costly repairs or replacements of essential components.
      • • High hardness can lead to scaling, a buildup of minerals on the equipment, plumbing, and jets. This can block water flow and reduce the efficiency of the system, leading to potential damage and decreased performance.

1. 1. Comfort and Safety
      
      • • Low hardness can also make the water feel harsh on your skin. Over time, it can cause the water to feel dry or uncomfortable. On the other hand, high calcium hardness can cause the water to feel slimy or slippery, which can be unpleasant for bathers.

What Happens if Hardness is Too Low?

When calcium hardness is too low, the water becomes aggressive and may start to dissolve the hot tub’s surfaces, plumbing, and equipment. This can lead to:

• • Corrosion of metal parts like the heater, pump, and jets.

• • Cloudy water that looks unattractive and may feel uncomfortable.

• • Faster wear and tear on your hot tub, leading to expensive repairs.

To prevent these issues, it’s crucial to maintain proper calcium hardness levels.

What Happens if Hardness is Too High?

If hardness is too high, it can cause scaling to form in your hot tub. Scaling occurs when calcium deposits build up on the surfaces of your hot tub, such as on the walls, jets, or plumbing. This can result in:

• • Cloudy water that makes your hot tub look dirty.

• • Clogged pipes and jets from the buildup of mineral deposits.

• • Reduced efficiency of the hot tub’s heating and filtration systems.

• • Uncomfortable water that feels slippery or slimy.

High calcium hardness can also reduce the effectiveness of sanitizers, such as chlorine or bromine, making it harder to maintain clean, clear water.

How to Test Calcium Hardness

You can easily test the hardness level in your hot tub using a test strip or liquid test kit. Simply follow the instructions provided with the test kit, and be sure to test the water regularly to stay on top of its levels.

How to Raise Calcium Hardness

If your hot tub water has low hardness (below 150 ppm), you will need to raise it to protect your equipment and improve the water quality. Here’s how you can do it:

1. 1. Use a Calcium Hardness Increaser: These products are specially designed to add calcium to the water. Simply follow the instructions on the product packaging for the correct amount to use based on the size of your hot tub.

1. 1. Add Calcium Chloride: Calcium chloride is a common substance used to raise calcium hardness levels. You can find this at pool supply stores. Be sure to dissolve the calcium chloride in water before adding it to your hot tub to prevent any undissolved solids from settling.

Once you add the calcium increaser, allow the water to circulate for a few hours and retest the water to ensure the calcium hardness level falls within the ideal range.

How to Lower Calcium Hardness

If your hot tub water has too much calcium (above 250 ppm), you will need to lower the level to prevent scaling and equipment damage. Here’s what you can do:

1. 1. Drain and Refill the Hot Tub: One of the easiest ways to reduce high hardness is by draining part of the water and replacing it with fresh water. This will dilute the mineral content and bring your calcium levels down.

1. 1. Use a Calcium Reducer: Some pool and spa supply stores sell products designed specifically to reduce calcium hardness levels. These products work by binding to the calcium and preventing it from forming scale.

After adding a calcium reducer, circulate the water and retest to ensure the calcium hardness is in the ideal range.

Conclusion

Calcium hardness is a vital aspect of your hot tub’s water chemistry. Keeping the calcium hardness level within the recommended range (150-250 ppm) ensures that the water remains clear, comfortable, and safe for soaking, while also protecting your equipment from damage. Regularly test the calcium hardness in your hot tub and adjust the levels as needed to maintain optimal water balance and extend the life of your hot tub. By staying on top of your water chemistry, you can enjoy a relaxing and trouble-free hot tub experience.

Have questions about your hot tubs water balance? Visit us in-store for a free professional water test!