how to Decrease Calcium Hardness In Hot Tub

How To Decrease Calcium Hardness In Hot Tub

Maintaining a hot tub is an overwhelming task. However, you can rapidly and easily reduce calcium hardness by draining the reservoir and filling it with fresh water. When your tub’s chemicals are balanced, maintaining it is as easy as testing the water’s chemical balance, and keeping the hot tub clean. In this article, you will learn how to decrease calcium hardness in your hot tub and maintain it with care.

What Is Calcium Hardness?

Calculating the water’s calcium hardness involves counting the calcium ions that are there. The water referred to as “hard” has a significant mineral content.

These minerals are mostly composed of carbonates, bicarbonates, chlorides, and calcium and magnesium sulfates. Mostly via washing over or through limestone and chalk rocks, the minerals enter the water. Hot tubs that have too high and too low calcium hardness can have serious issues. Here are a few:

Low Calcium Hardness:

  • Surface pitting on a hot tub
  • The surface of the tub is etched.
  • Tile grout dissolving
  • Etching on the hot tub surrounds’ concrete

High Calcium Hardness:

  • Hazy water
  • Rough edges in the tub
  • Filter blockages and decreased circulation
  • ‘Blotchy’ white spots on the tub’s surface

How to Decrease Calcium Hardness In Hot Tubs

If you seem to have come across the symptoms of high calcium hardness in your Hot tub here are a few steps you can follow to safely decrease calcium hardness in your hot tub.

Testing Calcium Hardness

You may check the calcium levels in your hot tub with a chemical test or a strip. Purchase a Calcium Hardness Test Kit at the tub supply or home improvement store. Use the kit to collect the tub’s water, then treat it by adding chemicals or a test strip. 

Wait for the water or the strip to change colors, and then compare the color to the label on the kit’s container. Aim for a calcium hardness of 250–350 parts per million (PPM). You must reduce the hardness if it is greater than 350 PPM.

calcium hardness test

Monitor And Adjust Chlorine Levels

As necessary, check the chlorine levels and make adjustments. When checked, the chlorine level should be between 1-3 PPM. Add chlorine pills to the skimmer basket if the chlorine level is low. Remove the chlorine tablets from the basket for 12 hours if it’s high. Retest the water after that to make sure the chlorine level is between 1-3 PPM.

Replace With New Water

Thoroughly vacuum the hot tub, then remove any calcium buildup using a scraper or chipper. Use a small hammer or paint scraper to chip away at thick calcium deposits on the tile or plaster before adjusting the calcium level in your tub. After that, vacuum the tub to remove any remaining debris and scum from the lining.

Using a hose or pump, drain part of the water from your Hot tub. Get a Pool Pump or create a siphon out of a hose, then put it in the tub. Place the pump’s discharge end in a location with good drainage, then wait until the water level is about 4-6 inches (10-15 cm) lower than the starting point.

Refill the tub with new water using a hose and a spigot. The end of a garden hose should be inserted into the tub after being connected to an outdoor connector. Once the spigot is turned on, allow the water to flow from the hose into the hot tub until it reaches its initial height.

pool pump

Retest The Calcium Hardness

Utilize a test kit to determine the Hot tub’s calcium hardness. Use a calcium hardness test kit to collect the freshly diluted water in a jar about 12 hours after you’ve finished the water replacement. Then, add a test strip or some of the kit’s chemicals to the water, and watch for a color change. To see the calcium level in parts per million (PPM), compare the color to the relevant one on the packaging.

Causes Of Excess Calcium In Hot Tubs

The presence of too much calcium in your tub is usually a sign of a more serious chemical problem. As most hot tub owners can attest, balance is key when it comes to water. If your tub’s pH is out of whack or your total alkalinity is either too high or too low, you’ll probably find yourself fighting algae, hazy water, and, of course, calcium deposits. 

High calcium has other causes besides chemical abnormalities. Another significant component is water temperature, which increases the likelihood of calcium precipitating out of the solution. Since calcium is more soluble in colder water, scaling of heater equipment is a regular occurrence.

How To Monitor Calcium Hardness In Your Hot Tub

After successfully changing water in your hot tub and reducing the calcium hardness to your desired need it is now very important to maintain the hot tubs for the long run. Here are a few steps you can follow to monitor calcium hardness in your hot tub.

Test Calcium Hardness In Tub Every 3 Months

Collect the water in a cup, and test it using a Calcium Test Kit from a home improvement store or pool facility. Depending on the kit, you may only need to submerge a test strip in the water or you may also need to add chemicals. Wait for the water or strip to change color, then check the color against the label on the container to determine the calcium content.

Lookout For Calcium Deposits In Walls And Equipment

The lining and equipment of the hot tub are covered in a thin, white layer known as scale or scum, which is one of the earliest indications of calcium hardness. As soon as you notice this film building in your tub, vacuum the damaged areas and do a calcium hardness test on the water.

Clean The Hot Tub Once A Week

When organic items like leaves and dead insects start to decompose in the tub, they might release toxins. To swiftly remove them from the tub’s bottom, use a Pool Vacuum with a brush attachment. Before they become too big, use the brush to wipe away calcium and algae deposits.

clean hot tub using a cleaner


What Causes Excess Calcium In Hot Tubs?

Excess calcium typically occurs when the pH of your Hot tub’s water is off. High pH, changing temperatures, and evaporation are typical offenders.

How Do I Find The Calcium Content In My Hot Tub?

The majority of testing kits detect calcium in addition to other crucial parameters like chlorine, pH, and alkalinity. Useful test strips might be a good place to start if you’re new to tub chemistry.

How Do You Remove Calcium Content From Hot Tub?

Using a pumice stone may do wonders for a plaster hot tub’s surface. However, you ought to use something less abrasive on the tile. Try using a scrub brush and vinegar.

Pool maintenance is as easy as monitoring the water’s chemical balance, making adjustments as needed, and keeping the pool clean once your pool’s chemicals are balanced. This concludes how you can decrease the calcium hardness in the hot tub.


Hi, I'm Shimul, the founder of Pooltub Life. I'm excited about sharing the latest outdoor living trends with you. My goal is to provide you with up-to-date information that will help make your POOL & HOT TUB stylish and enjoyable. Read About Me More । Follow on Facebook

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