The Complete Guide to Testing and Maintaining Calcium Hardness in Hot Tub

Are you experiencing calcium buildup in your hot tub? and looking for the best way to get rid of it?

Calcium hardness, or calcium carbonate, is made up of high levels of calcium and magnesium in the water, and it can lead to scaling, cloudy water, and equipment damage. Maintaining the right calcium hardness levels and balanced water in your hot tub is vital for a healthy and happy spa experience. In this article, we will discuss how to decrease calcium hardness in hot tub with some simple methods so you can enjoy calming soaks without worry!

What is Calcium Hardness?

Calcium hardness refers to the amount of calcium ions present in the water of a hot tub or spa. Calcium is an essential element necessary for the proper functioning a hot tub or spa, but if the calcium levels are too high or too low, the water chemistry balance can be affected, leading to corrosion or scaling.

The ideal range of calcium levels in a hot tub or spa water should be between 150 and 250 ppm (parts per million). If the calcium level in the water is too low, the water can become too corrosive. This can damage the hot tub or spa. On the other hand, if the calcium level is too high, the water may become too hard and cause scaling on the surface of a hot tub, as well as bathing suits and other materials.

To maintain the proper range of calcium level in a hot tub or spa water, it is essential to regularly test the water and adjust the unbalanced water as needed.

Testing Calcium Hardness in Your Hot Tub

To test the calcium hardness in hot tub water, you’ll need to buy a calcium testing kit online or from a pool or spa supply store. These kits often include test strips or a liquid reagent. When doing the test, follow the instructions included in the kit. Fill a plastic cup or test tube with some water from the hot tub, then add the reagents or dip the test strip into it. The color change indicates the level of calcium hardness, which you can compare to your ideal hot tub range.

Uncovering the Mystery of Elevated Calcium Hardness in Your Hot Tub

Few factors that can contribute to elevated calcium hardness levels in a hot tub:

  1. Source water contains hard water: if source water contains a higher concentration of minerals, including calcium, which can increase the calcium hardness level.
  2. Using calcium-based sanitizers: Some sanitizers, such as calcium hypochlorite, can increase the calcium hardness level in your hot tub.
  3. Using products that contain calcium: Some hot tub chemicals, such as pH increasers and algaecides, can contain calcium, which can increase the calcium hardness level.
  4. Using a calcium hardness increaser: Adding a calcium hardness increaser too much in your hot tub can increase the calcium hardness level.
  5. Evaporation: As the water in your hot tub evaporates, the minerals in the water become more concentrated, which can cause the calcium hardness level to increase.

The Impact of High Calcium Hardness on Your Hot Tub

High calcium hardness levels in hot tubs can lead to various adverse effects. The high levels of calcium in the water can cause scaling on the hot tub’s surfaces, making it difficult to clean and maintain. Moreover, it can also cause the water to become cloudy and discolored. If the calcium hardness is not addressed, it can also cause damage to the hot tub’s mechanical parts, such as the pump and heater, leading to costly repairs. High calcium hardness levels can also make the water feel abrasive against the skin, potentially leading to dryness and irritation. It is essential to regularly test the calcium hardness in hot tubs and take steps to keep it in the recommended range. This will help ensure the hot tub is safe to use and maintain its long-term performance.

The Impact of Low Calcium Hardness on Hot Tub Water

A low calcium hardness level in a hot tub can cause several issues. When the calcium hardness is low, the water conditions might become more corrosive. This can cause damage to the pipes and equipment of the hot tub, including the heater, pump, and jets. Hot tub metal components may disintegrate if the calcium hardness is extremely low. Furthermore, low calcium hardness can promote bacteria and algae growth, producing slimy water with an unpleasant odor.

How to Decrease High Calcium Hardness Level in Hot Tub

If you have determined that the calcium hardness level in your hot tub is too high, there are several steps you can follow to decrease it:

Drain some of the water from the hot tub: Depending on the size of your hot tub and the severity of the high calcium hardness, you may be able to simply drain some of the water and refill it with fresh, low-calcium water. This is often the quickest and easiest way to lower the calcium hardness level.

Use a water softening product: Various water softener products can help lower the calcium hardness level in your hot tub. These products usually work by replacing the calcium ions in the water with sodium ions, which can help reduce the water’s overall calcium content and create soft water. Follow the instructions on the product label carefully to ensure that you use it correctly.

Use a pH reducer: High calcium hardness is often accompanied by high pH levels. By lowering the pH of the water, you can dissolve calcium deposits and reduce the overall hardness of the water. A pH reducer will not directly decrease the calcium hardness level in your hot tub. However, it can indirectly affect the calcium levels in your hot tub by helping to prevent the formation of scale, which is a buildup of calcium and other minerals on the surfaces of your hot tub.

Use a water softener: A water softener can help to remove excess minerals from the water, which can help to reduce the calcium hardness level. There are a variety of water softeners available for hot tubs, so it’s essential to choose one that is compatible with your specific hot tub.

How to Adjust the Low Calcium Hardness Level in Your Hot Tub

Use a calcium hardness increaser: A calcium hardness increaser is a chemical specifically developed to boost the calcium levels in hot tub water. They are typically made with calcium chloride, which helps to increase the calcium hardness level. To use a calcium hardness increaser, you will need to follow the instructions provided by the manufacturer.

Add calcium-rich additives: A variety of additives can be added to the hot tub or spa water to increase the calcium hardness level. These include calcium chloride, calcium carbonate, and other chemicals. When using these products, ensure that they are used safely and effectively.


Benefits of Maintaining Adequate Calcium Hardness

Maintaining a balanced calcium hardness in your hot tub is important for several reasons. First, it helps prevent corrosion or the buildup of scaling on metal parts and damage to the hot tub. Also, adequate calcium water hardness helps to stabilize the water’s pH level. That helps control overall water chemistry.

In conclusion, it is crucial to maintain the correct calcium hardness levels in your hot tub to ensure its longevity and safety. Fortunately, there are several ways to decrease calcium hardness, such as adding fresh water, using a calcium-reducing chemical, or installing a water softener.

Check out our article ”Tips for Effective and Efficient Hot Tub Maintenance” for the best hot tub upkeep.


What is the optimal calcium hardness level for a hot tub?

A hot tub’s optimal calcium hardness level is between 150 and 250 parts per million (ppm).

How can I test the calcium hardness level in my hot tub?

You can test the calcium hardness level in your hot tub using a test kit available on the market.

How often should calcium hardness be tested in a hot tub?

 Calcium hardness should be tested in a hot tub once a week. 

What are the consequences of having too low or too high calcium hardness in a hot tub?

Low calcium hardness can cause pool or hot tub water to be slimy and have undesirable chemical reactions to the hot tub maintenance chemicals. High calcium hardness can cause cloudiness in the pool, poor balance, and scaling problems.

Is calcium hardness the same as alkalinity?

Calcium hardness and alkalinity level are two significant factors in your pool, but they represent different concepts. Calcium hardness measures how much calcium carbonate is dissolved in water. Alkalinity is a measure of how alkaline the water looks.

Does calcium hardness affect pH or alkalinity?

Yes, If the calcium hardness level is too high, then the pH and alkalinity will be increased.

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