How to Raise or Lower Water Hardness in a Hot Tub?

Having clean hot tub water relies heavily on the right water hardness level. But the problem is the freshwater that you fill your hot tub with doesn’t always have the right water hardness for your hot tub.

But not to worry, this post reveals a brilliant strategy that can help you to raise or lower water hardness in a hot tub. So let’s dive in.

How to Raise or Lower Water Hardness in a Hot Tub

What Does Calcium Hardness Mean?

Calcium hardness means the amount of dissolved iron in the water. Every source of water has irons in it, usually calcium and magnesium. The amount of these dissolved irons is what is referred to as the calcium hardness of the water.

When the water is hard, that means the amount of dissolved calcium and magnesium in it is high. When the water is soft, it means that the amount of dissolved calcium and magnesium in it is low. It’s important to have a balanced calcium hardness level in your hot tub water to prevent damages to the hot tub and its components.

Related Read: How To Get Iron Out of Hot Tub Water?

What Should the Calcium Hardness Level in My Hot Tub Be?

The calcium hardness level in your hot tub should be between 150 PPM (parts per million) and 250 ppm with 180 ppm being the sweet spot. If the calcium hardness is too low, then you will have soft water in the hot tub that can cause hot tub foam and cloudy spa water.

If the water hardness is too high, the hot tub will be affected by the hot tub scale. Don’t worry, we’ll discuss more on the effects of low and high calcium hardness levels in your hot tub later in this post. But for now, let’s check out the differences between calcium hardness and water hardness.

Calcium Hardness vs Water Hardness

There is no difference between calcium hardness and water hardness. Calcium hardness and water hardness are terms that are both used to refer to the amount of dissolved irons in the water. Another term used in this case is total hardness.

Total hardness refers to the amount of dissolved calcium and magnesium in the hot tub water. So in other words, water hardness, calcium hardness, and total hardness all mean the same thing.

If you lower the water hardness of your hot tub water, you are also lowering the calcium hardness and total hardness of the water. It’s the same case if you raise the calcium hardness of the water.

The amount of calcium and magnesium in your hot tub water determines how hard the water would be. So how do you figure out the amount of dissolved irons in your hot tub water? The answer to this question is coming up next.

How Do I Test for the Hardness of My Hot Tub?

You can test for the hardness of your hot tub water by using a hot tub test strip, a liquid testing kit, or a digital tester. The ideal water hardness level should be between 150 ppm and 250 ppm (parts per million). Any reading below or above this range is wrong for your hot tub water to have.

How Do I Test for the Hardness of My Hot Tub?

To test for the calcium hardness, you should take a sample from your hot tub water and test it with a test strip. It’s more convenient using a sample of the water than using the whole hot tub water.

Alternatively, you can take a sample of the water in the hot tub to your local pool store. Many stores that sell hot tub and pool supplies also offer services for testing the water. So if you can’t test the water by yourself, you can get professional help but be prepared to pay for the service.

There are also a few tips that can help you determine if the calcium hardness of your hot tub is off. If you notice that the water leaves a slimy feel on your skin – like you used soap on your skin after soaking in the hot tub water, that means that the water has a high amount of dissolved irons in it. Hard water often has a slimy feel on the skin when used.

On the other hand, if you notice that there is foam on the hot tub water – like you added detergent to the water, this means that there is a low amount of dissolved irons in the water. These tips can let you know if the calcium hardness in your hot tub is off but the only way to be sure of the calcium hardness level is to have the water tested.

How to Raise Water Hardness?

If your test results showed that the water hardness in your hot tub is below 100 ppm, then you need to raise the calcium hardness immediately to eliminate the risk of corrosion. The best way to raise the water hardness in your hot tub is to add calcium chloride or calcium hardness increaser to the water. But before you can add calcium chloride to the water, you need a few tools.

How to Raise Water Hardness?

  • A pair of gloves
  • A bottle of calcium chloride or calcium hardness increaser
  • A large bucket (optional)

Now, let’s get to work.

Turn on the Jets and the Circulation Pump

Turn on the jets on a low setting by pressing the jet button. Pressing it twice increases the jet power. You should also turn on the circulation pump. Why? You’ll find out in just a sec.

Mix the Calcium Hardness Increaser With Water

This step depends on the brand of calcium hardness increaser you buy. Some calcium increasers will require you to mix the content with water and some can be used directly from the container.

To know if you need to mix yours, check the instructions on the container of the calcium hardness increaser that you purchased. Ensure to follow all the instructions on the container when mixing the content. If you can use yours directly from the container, then you can skip this step.

Related Read: Can You Mix Different Brands of Hot Tub Chemicals?

Add the Calcium Hardness Increaser to the Water

While the hot tub is running, add the calcium hardness increaser in the right amounts to the water.

The reason for turning on the circulation pump and jets earlier is to keep the water in circulation. If the water isn’t being circulated, you wouldn’t get good results when you add the calcium hardness increaser to the water. This is because the calcium hardness increaser will most likely be concentrated in some parts of the hot tub water. The best way to be sure of even distribution is to keep the water in circulation.

Vacate the Hot Tub

After adding the calcium hardness increaser, you shouldn’t use the hot tub till you are sure the calcium hardness of the water has been raised accordingly.

This might take up to 24 hours or more depending on the brand of calcium hardness increaser that you used.

Test the Water

After a few hours, you should test the water in the hot tub to be sure the calcium hardness level has been raised. If the calcium hardness level is still below 180 ppm, it means you didn’t add the right amount of calcium hardness increaser to the water. You should give it a second try by following the steps above as you did earlier.

As an expert tip, always ensure to follow all the instructions stated by the manufacturer while raising the water hardness level. When the calcium hardness is within the recommended range, then you can use your hot tub.

Now you know how to raise the calcium hardness level in your hot tub. But how do you lower the calcium hardness level? Let’s find out.

How to Lower Water Hardness?

If the test results showed that the calcium hardness level of your hot tub is above 250 PPM, then you need to lower it immediately to prevent hot tub scale. The best way to lower water hardness is to drain the water. But there are a few steps to follow before you do that. Let’s get to work.

How to Lower Water Hardness?

Turn Off the Hot Tub

It’s never a good idea to drain your hot tub when it’s still running. You can also turn off the GFCI breaker to cut off all power supply to the hot tub temporarily.

Determine How Much Water You Need to Drain

The next step is to determine how much water you need to drain from the hot tub. If the calcium hardness level is a bit above the recommended range (250 PPM), then you need to drain a few gallons of water.

If the calcium hardness level is way above the recommended range or over 400 PPM, then you need to empty and clean the hot tub.

Drain the Hot Tub

To drain the hot tub, start by locating the drain valve. The drain valve is usually at the base of the hot tub. When you locate it, connect a garden hose to the drain valve and open the valve to allow the water to escape.

If you want to drain a few gallons of water, ensure to keep tabs on the water level in the spa so you don’t drain more than the needed amount. If the calcium hardness level is very high, usually over 400 PPM, then you should completely drain the hot tub.

Add a Scale Control to the Water

If you drained part of the water, you should top up the remaining water by adding fresh water to the hot tub. Then add a scale control product to the water to prevent the calcium levels from rising again.

If you drained the entire hot tub because of a very high calcium hardness reading, then you don’t need to add any scale control product, at least not yet. If you emptied the hot tub, ensure to clean it and refill the hot tub with fresh water.

Then test the water for water hardness. If it’s low, you should incense it by adding a calcium hardness increaser. After that, you can add a scale control product to the water.

Test the Water

After draining and refilling the hot tub either partially or entirely, you should test the water to be sure the calcium hardness level has been lowered. If the calcium hardness has been lowered below 250 PPM, then you can soak in the hot tub again.

What Happens if Calcium Hardness Is Too High?

When the calcium hardness in your hot tub is too high or above 400 PPM, it will damage your hot tub and its components by causing hot tub scale. Hot tub scale is a whitish coat that appears on different parts of your hot tub. The scale is often flaky and can be very difficult to remove.

The hot tub scale usually attacks the metal components of the hot tub like the heater, the jets, and the shell of the hot tub. The hot tub scale will cover the surface of the heater making it difficult for water to reach the heater. This can damage the heater by causing burnout of the heating mechanism. The scale can also affect the circulation pump by accumulating in the pump’s impeller.

A high calcium hardness level can also cause cloudy spa water, low water flow, and unbalanced water chemistry. Eventually, you will find yourself spending hundreds of dollars on repairs and replacement of your hot tub’s components if there is too much calcium hardness in the water. But does this mean a low calcium hardness level is safe for the hot tub? Let’s take a closer look.

Related Read: How To Prevent Hot Tub Scale?

What Happens if Calcium Hardness Is Too Low?

When the calcium hardness level in your hot tub is too low or below 100 PPM, it will damage the hot tub and its components by causing corrosion. Corrosion means that the water in the hot tub will start to eat away at the metal components of the hot tub. Corrosion will damage the working parts of your hot tub quickly and can be difficult to stop.

If the calcium hardness level is low, you will have soft water in the hot tub and soft water is anything but soft. When the water in the hot tub is soft, it means that the water does not have enough calcium in it.

So the soft water starts to eat away at the metal parts of your hot tub like the heater and jets in search of calcium.

Corrosion will cause dents and holes in the working parts of your hot tub causing them to malfunction and break down prematurely.

A low calcium hardness level in the hot tub water can also cause foaming in the water, staining on the shell of the hot tub, and discoloration.

Final Words

Overall, having a high or low calcium hardness level in your hot tub is not unusual since many water sources don’t have the right calcium hardness level needed in your hot tub.

But you need to stay ahead of the situation by testing the water regularly for calcium hardness level. If you notice the water hardness is below or above the recommended range, you should fix it immediately to prevent damages.

Leave a Comment