How To Reduce Calcium Hardness In a Spa Pool

Calcium hardness can affect the water quality and component life in your spa pool and surrounding areas if levels are not kept within the safe range.

But, what is calcium hardness exactly and why is keeping it balanced so important? Let’s dive straight into the deep end!

This article covers:

• What is Calcium Hardness?
• Are Water Hardness and Calcium Hardness The Same Thing?
• Why is Water Hardness in a Spa Important?
• What Happens If The Water Is Too Hard?
• What Happens If The Water Is Too Soft?
• How To Measure Water Hardness/Calcium Hardness

Key Takeaways

• Calcium hardness is the amount of dissolved calcium in your spa water and needs to be balanced.
• High calcium levels cause scaling, cloudy water, and blocked pipes.
• Low calcium levels can damage spa surfaces and equipment.
• Test water hardness using test strips, liquid kits, or professional testing.
• To lower hardness, partially drain and refill, use a filter, or apply scale control.

What is Calcium Hardness (Hard Water In Spa Pool)?

Calcium hardness refers to the level of calcium that is dissolved in your spa pool water.

It will vary depending on the calcium in your water source.

Rainwater bore water or river water will all have different levels of hardness.

Depending on where your water is sourced your calcium hardness will differ and needs to be adjusted accordingly.

Are Water Hardness and Calcium Hardness The Same Thing?

Just to clear things up from the start, calcium hardness and water hardness are the same things.

They are often used interchangeably to refer to the calcium levels in the water. If water is considered “soft” it means the calcium levels in the water are lower, and if it is considered “hard” then the calcium levels are higher.

It is worth noting that some measurements, like total hardness, refer to the combined levels of calcium and magnesium in the water. However, you can still work off of total hardness levels to balance water hardness effectively.

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Why is Water Hardness in a Spa Important?

Maintaining the right water hardness is essential for keeping your spa in good condition.

Too much or too little calcium can lead to problems over time. Here’s why it matters:

• Prevents plumbing damage – Calcium buildup can clog pipes and spa jets.
• Protects circulation pumps – Scale deposits put extra strain on the system.
• Keeps water clear – High calcium levels can make spa water cloudy.
• Avoids long-term damage – Imbalanced water hardness can ruin spa components.
• Ensures proper maintenance – Regular testing helps keep calcium levels in check.

What Happens If The Water Is Too Hard?

If your spa water has too much calcium, it can lead to several problems that affect both the water quality and the spa’s internal system. Here’s what can happen:

• Long-term damage – High calcium levels can harm the spa’s internal system.
• Blocked pipes – Excess calcium builds up in hidden areas, restricting water flow.
• Scaling on surfaces – Calcium deposits create a rough texture on the spa shell.
• Cloudy water – Floating calcium particles can make the water appear murky.
• Skin and eye irritation – High calcium levels can disrupt pH balance, increasing irritation risks.

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What Happens If The Water Is Too Soft?

Soft water is lacking calcium and will leach calcium from wherever it can to make up for the low levels. This means that the water will start to dissolve any surface or equipment that contains calcium such as plaster, grout, or concrete decking.

If water hardness is left unchecked for too long, low calcium levels can cause damage to the spa jets, heating elements, pool deck, and possibly the spa shell as these parts may contain traces of calcium. Lastly, low calcium in water can cause a slimy feel to the water and contribute to spa foam.

How To Measure Water Hardness/Calcium Hardness

To make sure your calcium hardness is at a safe level, you will need to measure it using some form of a test kit or test strips. The most common ways to test water hardness are:

1. Measure calcium hardness with a total hardness test strip

Total hardness measuring test strips are easier to use than any other method but are generally much less precise compared to other methods. These strips test the total hardness including the magnesium levels.

2. Measure calcium hardness with a liquid test kit

Liquid test kits are more manual than test strips but are often much more accurate and precise, as they can measure the calcium level on its own down to 10 ppm increments.

3. Take a sample of your water to a pool supply store

If testing your water hardness yourself is too daunting, you can take a sample of your water to your nearest spa pool supplier for a professional water test.

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How To Raise Water Hardness In A Spa Pool

Once your water has been tested and the results show a low water hardness, you can increase hardness by adding calcium chloride, a common calcium hardness increaser. Here’s how to do it:

• Use calcium chloride – This is the recommended product for increasing water hardness.
• Add slowly – Avoid overshooting the balance, as hard water is harder to fix than soft water.

Pro tip: Avoid mixing with soda ash or baking soda. Adding these too close together can make the water cloudy.

How To Lower Water Hardness In A Hot Tub or Spa Pool

If your spa water has high calcium levels, you may need to drain and refill the water to restore balance. The extent of draining depends on how high the calcium levels are. Here’s what you can do:

• Partial drain and refill – If calcium levels are slightly high, replace some water and add a scale control product weekly.
• Full drain and clean – If calcium levels are too high, completely drain, clean, and refill the spa.
• Use a hose filter – When refilling, use a filter to reduce calcium from the water source.
• Apply a scale control product – Helps manage calcium buildup and maintain balance.

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Can I use a mineral softener in my spa?

Yes, the Zodiac^® MagnaSpa™ mineral spa treatment is a mineral-based product that can also help soften your spa water, making it feel smoother.

Other Factors In Balancing Spa Water

Along with balancing calcium levels in your spa pool water, you need to take into account your pH balance, aka the water acidity, chlorine levels, and water temperature.

Keeping your water pH balanced is the most important, as this is ultimately what causes your water to be either corrosive or scaling and is affected by the other factors in spa pool water balancing.

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Spa Chemicals To Keep Your Spa Water Crystal Clear:

Depending on what type of spa system you have, you can add a variety of safe and effective spa chemicals to keep your water crystal clear. Both chlorine and saltwater spas use chlorine as their main anti-bacterial and spa sanitiser, but chlorine is not the only chemical you can consider.

Here is a list of chemicals you can keep handy to maintain a perfect spa pool:

• Spa sanitiser
• Spa shock
• Defoamers
• Scale control
• PH adjusters

Got more questions?

Talk to us or email us your spa questions and we'll be happy to help!