How to Soften Pool Water (3 Proven Methods)

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If you live in a hard water area, think twice before you use your water to fill a pool or hot tub. Pool water should be moderately hard (to prevent corrosion) but hard or very hard water will cause scaling that could damage your pool’s fixtures and fittings.

In this guide, we’ve shared the best methods to soften your water down to an acceptable hardness level and achieve perfectly balanced pool water.

πŸ“Œ Key Takeaways:

  • Hard water forms limescale on your pool pump, steps, gutter grates, filter, and other equipment.
  • The best methods to soften pool water are by adding softening chemicals, draining part of the pool and replacing the hard water with softer water, and using a pool flocculant.
  • We don’t recommend using water softeners for swimming pools. A salt-based softening system will produce soft water, rather than simply bringing your calcium hardness down to the appropriate range.

🚱 What Is Water Hardness?

First, a quick refresh on the actual definition of water hardness, and what it means for your pool.

Water hardness, or calcium hardness, is a measure of the dissolved calcium carbonate in water. Calcium is naturally occurring in surface water and groundwater sources, especially in areas with lots of limestone and similar sedimentary rocks.

The most characteristic sign of water with a high calcium hardness is limescale deposits. Limescale is a chalky gray or white substance that’s rough to touch and difficult to remove once it sticks. It can damage and clog pool equipment if hard water is used in the pool.

Limescale deposits in pool

πŸ€” What’s Classed As Hard Water?

Got an inkling that your water might be hard, but not sure?

Buy a water hardness test from your local pool supply store or online. Dip the test strip into you pool and wait for it to change color to indicate your water hardness.

A calcium hardness reading of over 250 PPM (parts per million) is considered hard in the context of swimming pools, and you may need to take action to reduce your water hardness level.

500 PPM of calcium hardness is considered very hard and you will definitely need to take action to prevent extensive damage to your pool equipment.

πŸ“ˆ What’s The Optimum Hardness Level For Swimming Pool Water?

So, what level of water hardness is best for a pool?

You might assume that achieving the softest water possible is the best outcome for your swimming pool’s water. Actually, though, this isn’t true.

Soft water is just the opposite of hard water: it contains very few-to-no minerals, meaning that it has minimal calcium hardness. If your water is too soft, it creates issues of its own.

Using soft water in a pool might cause:

  • Corrosion of your pool’s shiny, metal parts
  • Foaming issues
  • Corrosion of soft parts (in hot tubs)
  • Corrosion of other pool surfaces that contain calcium, such as concrete or plaster pool walls

So, to prevent hard and soft water issues in your pool, you need to achieve a perfect balance between the two.

For pools with a vinyl or fiberglass liner, a calcium hardness level of about 150-225 PPM is considered ideal.

For plaster or concrete pools, the hardness range extends up to 275 PPM.

We’ve shared the best methods to achieve these optimal hardness ranges below.

Pool water hardness test

πŸ“– How To Soften Pool Water: 3 Highly Effective Methods

Read on for our top 3 recommendations for softening the water in your pool:

Method 1: Drain & Replace Some Of The Water

The quickest and easiest method to reduce your pool water’s hardness is to drain some of the pool and refill it with water with a lower calcium hardness level.

Turn off the pool pump, then use a pump to drain a few inches of water. Replace this with water that contains little-to-no calcium minerals to bring down the overall hardness. Turn the pump back on.

The water will circulate in the pool, and the new addition should gradually bring down the pool’s calcium hardness.

This method will only work if you have access to fresh, naturally soft water (ideally not salt-softened water).

Method 2: Use A Chemical Water Softener

Most pool owners tackle hard water with a chemical water softener designed specifically for use in pools and hot tubs. You can buy chemical pool softeners from most pool supply stores for less than $30.

The exact steps for using a chemical pool softener depend on the instructions on the bottle. Here’s a general overview of what you will need to do:

  1. Turn off your pool equipment.
  2. Gather your materials. You’ll need a 5-gallon bucket, water from your pool, and the chemical softener.
  3. Add pool water to fill the bucket halfway.
  4. Add the chemical softener. Follow the steps on the bottle to add the correct dosage based on your pool size.
  5. Mix the softener chemicals with the water, then pour the contents of the bucket into your pool and switch on the pump.
  6. Wait up to 24 hours, then use a test strip to check that your pool’s total alkalinity has dropped to the optimal range. If it hasn’t, you may need to add more chemicals to your pool.
Chemical softener for pool

Method 3: Use A Pool Flocculant

We recommend method 1 or 2 for most scenarios. however, if you don’t have access to soft water or a chemical softener, then you can use a pool flocculant to encourage the excess calcium in your water to clump together. You can then vacuum your pool or use a sand filter to remove the clumps.

Make sure you turn off your pool pump and filter before adding a flocculant to your water. You will need to thoroughly brush the walls to lift as much limescale staining as you can.

This method is a suitable short-term solution for reducing water hardness in your swimming pool, but it takes too much time for us to recommend it for long-term calcium hardness management.

πŸ€” Can You Use A Water Softener System For Pool Water?

We do NOT recommend using a water softening system to soften pool water. Why? Because a water softener doesn’t only reduce excess calcium and bring water to optimum hardness levels – completely eliminates calcium hardness, resulting in soft water.

We’ve already mentioned the potential issues with using water that’s too soft in your swimming pool, including corrosion and unwanted foaming.

There’s no effective way to set your water softener to only partially soften your pool water to achieve an optimum hardness, as you can with the other softening methods mentioned in this guide.

Plus, when you use a water softener for softening pool water, you’ll end up adding water softener salt to the water. This will give the water an unpleasant slippery feel, and salt-softened water contains additional components with corrosive properties – bad news for pools.

Some manufacturers claim that their water softening salts are safe for pool use, but for the sake of the longevity of your pool equipment, we would always recommend a chemical water softener first.

πŸ“‘ Final Word

If you want to avoid issues with corrosion, limescale, and irreversible damage to your pool equipment, you need to achieve perfectly balanced pool water.

Luckily, reducing your pool water’s hardness is fairly inexpensive and easy enough for most folks to manage. No need to call in an expert.

If you accidentally reduce your calcium hardness level too much, don’t panic! It’s easy to resolve this issue, too – just add calcium chloride or a similar calcium hardness increaser to your swimming pool. Add it gradually to bring up your pool’s calcium hardness to the appropriate range.

Pool flocculant and other pool cleaning tools

πŸ‘‰ Continue Reading: Is it Safe to Fill your Pool with Well Water?

❔ How To Soften Pool Water: FAQ

Do you need a water softener with a pool?

No, we don’t recommend installing a water softener system to treat the water in your pool. Water softeners exchange all calcium ions with sodium ions, resulting in completely soft water. Since your goal is simply to reduce your water’s calcium levels down to the optimum hardness (around 150-250 PPM), a water softener will actually create issues of its own. Soft water is very corrosive and could damage your pool pump, walls, and other pool equipment.

Should pool water be softened?

You will only need to produce softened water for your pool if your calcium hardness level is higher than 250 PPM. This level of hardness will result in limescale formation, damaging your pool components. If your water hardness range is already optimum (150-225 PPM), you won’t need to soften it.

What happens if pool hardness is high?

If pool hardness is high, what will happen is that limescale from your water supply will build up on the pool’s surfaces. This scale formation may reduce the lifespans of your pool components and cause clogging. It’s also very difficult to remove, especially if it’s allowed to build up over time.

Can I put salt in my pool to soften the water?

Yes, if you’re in a pinch and don’t have access to any of the more effective pool water softening methods available, you can use salt in your pool for softening purposes. Pool salt is usually used for sanitization purposes, but it may also reduce calcium hardness somewhat. The reason why we don’t recommend adding water softener salts straight to your pool is that they’re designed to dissolve slowly in water, so they’ll likely end up sitting at the bottom of your pool. They’ll also result in cloudy water in your pool.

Will baking soda soften pool water?

No. Baking soda can be used to maintain your pool’s optimal alkalinity and pH, but it isn’t designed to produce soft water. The most effective water softening option for pools is to use a chemical water softener (which you can buy online or from your local pool store).

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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