How To Soften/Reduce Hardness In Swimming Pool Water

How To Soften/Reduce Hardness In Swimming Pool Water

Swimming Pool is a great place to rejuvenate with your family. I feel there can’t be any other better way to spend your weekend and vacations. 

Lately, I observed some deposits on the pool surface and similar patches along its sides. My immediate action was to empty the pool and clean it with soap and vinegar solution. It got cleaned but the same deposits reappeared after a few weeks. 

Then I recalled an infomercial I saw during a movie about water hardness in our area and how it can be handled by some chemical treatment. I quickly related my pool’s problem with water hardness. 

I did some research and learned that the hard water affects the pool surface as well corrodes the plumbing of the pool. It could also end up in damaging the whole pipes and pump system if the hardness levels are extremely high. 

The first time you see that the pool water is looking cloudy it must ring warning bells for you. Wait no more to try some random tricks for cleaning the water. Get the pool water tested for hardness level and follow the prescribed remedies. 

Read along for a basic understanding of the problem and then proceed to spend your money on the right treatment. It must not be delayed at any cost because if you do you may end up paying a huge bill for damaged plumbing and hard to clean pool surface that can be corrected only by replacing it. 


What are the Reasons for Water Hardness?

Pool water can get affected by presence of elements like copper. Pool water must be treated for copper. But, scientifically speaking water hardness is related to the excessive presence of certain elements like Calcium and Magnesium in water.   It is a common problem if the PH level of water is on the higher side of alkalinity. It is basically dependent on the area you live in. 

Accepted levels of water hardness for different pool types

The people who have swimming pools or wish to own one must take care that pools must have water with hardness levels between 200 and 400 ppm. 

A plaster pool is easily affected by even lower levels of water hardness so they must be filled with water with 180-220 ppm hardness.  Same is the case with vinyl pools which can accommodate 150-250 ppm hardness in water.

How to Measure Hardness of Pool Water

The hardness of the pool water is a very common problem and I frequently get complaints from my friends and others who trust me for the health of their pools. Well after many years of experience and different views about controlling pool hardness I am listing down the easy and cost effective methods that you can follow. 

But before jumping on to these methods you must know about the health of your pool. The check on the hardness can be done easily with a dip test. For that, you need a hardness test kit. All you need to do is dip the test strip about 18 inches deep from the water level. If you are not too sure about the right depth then read the instructions given on the kit and do as suggested by the manufacturer. 

Now you can take out the test strip and let it settle for a few minutes. It will take a while that the test strip to change to the exact color for reading the hardness level as indicated in the enclosed comparison indicator. Match the color of the strip to the exact color on the test strip. You need not worry if the result is anything between 200 and 400 ppm. But if you have a reading above this range then chose any method mentioned in the next segment to get back your healthy pool. 

Methods to Reduce Hardness of Pool Water

Replacement Method

The first method I am describing is the simplest. All you need to do is take out some amount of hard water from your pool and replace it with the softened water to balance the hardness of remaining pool water.

This process can be done every year to keep the pool in good shape. Using your pool’s drain equipment you have to drain out about one-third of the water.  The drained water can be diverted to your plants or kitchen garden to minimize water wastage. Once the desired quantity of hard pool water is drained you have to add the soft water. The source can be any. You can get the water from the home softening system or can hire a water supply carrier to supply treated water from other location.

Many cities have some kind of local pool supply professional services in the areas where hard water is a critical problem. Such a supply is a very easy and convenient method of reducing the hardness of pool water since you don’t need to wait any longer. As soon as the softened water supplier takes out the hose you are ready to jump in and enjoy the splashing moments in your pool again. 

Adding Softening Agents Available Commercially

If you don’t have a home softening system or a softened water supply company in your region you are left with the second method of reducing the hardness of pool water. You have to buy a commercially available hardness reducer and add it to your pool water.

Different softening agents have their own specific manufacturer instruction to be followed while using. You need to read these instructions very carefully and have to know about the pool and the level of hardness to achieve the required softness. 

Also, make sure to use only the recommended amount of chemicals and use a clean plastic bucket to do all the mixing and stirring very carefully. Don’t add the whole solution at one spot in the pool. Instead, you have to add this solution slowly along all the edges or complete circumference of the pool.

Now is the time to mix the water and the added solution. This needs the services of your pool pump. You have to leave your pool pump on for one complete day. At the end of one day increase the pH level of water so that it stays between 7.8 and 8.2.


You can use borax or soda ash for this.  Check the hardness after a week and if it is at the desired level you have all the right to show that you have lost your patience and jump in the pool.

Bryan Mallory

My name is Bryan Mallory and I have over 25 years of experience in swimming pool, spa maintenance and repairs. With my experience and knowledge I can return your pool back to its best and keep it in peak condition.