Pool Calcium Hardness

Understand Calcium Hardness & Pool Water Maintenance. Learn Swimming Pool Water Chemistry & Hard Water Solutions.

Calcium Chart ~ Visitor's Questions

How To Test Your Pool Water Hardness 

The ideal range for perfect swimming pool chemical maintenance is 150ppm-250ppm, not 300 - 350ppm or higher.

This is especially true for saltwater pools and salt water pool system.

If you add any more calcium hardness increaser your salt cells might calcify and burn up, shortening its life. You also run the risk of having hard water scale at the water line.

Watch the video as I test a pool's CH using the Taylor K-2006 pool test kit.

Water is hungry for calcium and will try to feed its appetite any way it can. Many times it will draw it from the plaster, which causes unsightly pitting, or from your filtration system, which will cause hard water deposits.

You've watched me take a pool's calcium hardness test in the above video. Now get all you need to have a perfect pool all swimming season. Simply click on the eBooks below to get started.

Keeping your calcium hardness level between 150ppm - 250ppm will prevent this from happening. Some areas of the country may have very soft water or very hard water.

You don't need take your tap water anywhere and have expensive tests performed. Simply call your local water company and ask them the calcium hardness of the water or use a good pool water test kit. 

Central Oregon has very very soft water, about 1ppm-2ppm. In places like Arizona, Nevada, Florida, and Southern California the hardness may reach 200ppm-300ppm or higher.

Pool Calcium Hardness

If you have a Hot Tub, spa, or heated pool, maintaining the proper calcium hardness in your water becomes even more critical.

Most swimming pool problems result from bad pool chemistry advice given at the wrong time.

Problems With Low Calcium Hardness

  • Pitting and etching of the plaster
  • Dissolved grout in your pool
  • Staining of the pool surface
  • Possible heater failure
  • Corrosive and scaling water
  • Supersaturation
  • Swimming pool stains

Problems With High Calcium Hardness

  • Skin and eye irritation
  • Cloudy swimming pool water
  • Clogged pool filters
  • Poor filtration
  • Calcium build-up and corrosion on heaters
  • Scaling of the pool water

This is according to the Langelier Index that has been used for above ground pool maintenance, inground pool maintenance, and salt water pool maintenance for decades. Keep in mind, proper balance of your swimming pool chlorine, pool pH, pool alkalinity, and hardness is of the utmost importance in having a safe and clear pool water. It will decrease your chlorine demand, muriatic acid use, pool stabilizer, and alkalinity increaser. 

One easy way to slow the progress of calcium rings at the water line is to keep the pH a bit more acidic, about 7.2 - 7.4.

Tap Water Calcium Hardness

When you have softer water, you may need to add Calcium Chloride to correct the hardness level. DO NOT make slurry or mix the calcium chloride in a bucket with water. It may “steam” up and cause severe burns. Have a designated chemical bucket pool pole to stir up other chemicals. 

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Also, when you add the calcium, you might have cloudy pool water. This is normal and should clear up with a few hours of filtration. If you have a salt water swimming pool with an in-line chlorine generator, be extra sure your calcium is at the correct level or else you may end up ruining your salt cells. The calcium will crust on the fins and before you know it, you're shelling out another $1000 for a new salt chlorine cell.

Broadcast it directly into the pool, starting in the deep end and working around the perimeter of the pool. Apply the calcium as you would use a salt shaker. Refer to the chemistry help chart to see the amount calcium chloride your pool needs for your pool water care.

Any store that sells swimming pool equipment supplies or discount pool chemicals can help with your calcium needs. 

Hard Water And High Calcium Fill Water

Having high calcium hardness (above 250-300ppm) in your tap water is very difficult to keep down. Reducing calcium hardness is difficult. You may either replace some or all of your pool water or have pool water trucked in.  

When filling your pool with fresh water, be sure to test the tap water for its hardness. This will give you a good starting point to see if you need to add calcium chloride or not.

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Unfortunately there is no quick and easy answer on lowering your swimming pool water hard water.

Chart - Raising Hardness With Calcium Chloride



(ppm) 1,000 5,000 10,000 15,000 20,000 25,000 50,000
10 2 oz. 10 oz. 1 1/4 lbs. 1 3/4 lbs. 2 1/2 lbs. 3 1/4 lbs. 6 1/4 lbs.
20 4 oz. 1 1/4 lbs. 2 1/2 lbs. 3 3/4 lbs. 5 lbs. 6 1/4 lbs. 12 1/2 lbs.
30 6 oz. 1 3/4 lbs. 3 3/4 lbs. 5 1/2 lbs. 7 1/2 lbs. 9 1/2 lbs. 18 3/4 lbs.
40 8 oz. 2 1/2 lbs. 5 lbs. 7 1/2 lbs. 10 lbs. 12 1/2 lbs. 25 lbs.
50 10 oz. 3 lbs. 6 1/4 lbs. 9 1/2 lbs. 12 1/2 lbs. 15 3/4 lbs. 31 1/4 lbs.
60 12 oz. 3 1/4 lbs. 7 1/2 lbs. 11 1/4 lbs. 15 lbs. 18 3/4 lbs. 37 1/2 lbs.
70 14 oz. 4 1/4 lbs. 8 3/4 lbs. 13 lbs. 18 3/4 lbs. 22 lbs. 43 3/4 lbs.
80 1 lb. 5 lbs. 10 lbs. 15 lbs. 20 lbs. 25 lbs. 50 lbs.
90 1 lb. 5 1/2 lbs. 11 1/4 lbs. 17 lbs. 22 1/2 lbs. 28 lbs. 56 1/4 lbs.
100 1 1/4 lbs. 6 1/4 lbs. 12 1/2 lbs. 18 3/4 lbs. 25 lbs. 31 1/4 lbs. 62 1/2 lbs.

Pool Water Testing For Hard Water

What is pool water hardness?

Water hardness is the makeup of the minerals (calcium, magnesium, iron, etc...) that are naturally found in tap and pool water.

When do I test for water hardness?

The best time to take any tests is in the late afternoon or early evening. Keep your pool’s hardness level between 150ppm-250ppm, not 350ppm or above.

Where do I test the water hardness?

The best place is either in the deep end of the pool or the furthest place from the filtration. Be sure to test you tap water as well so you’ll have the proper starting point with a freshly filled pool.

Why should I test for hardness?

Water hardness is one of the elements that make up the test routine. Included in this are chlorine, combined chlorine, CYA/pool stabilizer, pH, and alkalinity. Water is hungry for calcium and will take it from any source it can get. By keeping your water’s appetite for calcium fed and at the proper levels (if your fill water has low calcium hardness) you will minimize corrosive and scaling water, pitting of the plaster, clogged heaters and filters, and eye and skin irritation.

These pool tips will save you time, money, and maybe even a few migraine headaches.

Go swim and have fun with your family and friends.

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If you have a water/chemical related issue, you must give your chemicals readings, type of filtration system, what you've done or are trying to do, etc.. I can only help if you give your chemical readings.

Cyanuric Acid
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What Other Visitors Have Said

Click below to see contributions from other visitors to this page...

Calcium Build Up 
I have a calcium ring around my pool. I saw your video but I learn better when someone actually teaches me hands on. I see you are based in Arizona …

Low Calcium Hardness White Flakes Clog Salt SWG 
We have a fiberglass in-ground pool, total of 34,000 gallons. This year we had water trucked in as our fill water is high in iron. This was soft water, …

Step 2 Taylor Calcium Hardness, No Red 
I test calcium hardness weekly in the following water venues using Taylor Test Kit: 300,000 gal outdoor pool (about 70 deg)(Accutabs) 23,000 …

Low Calcium In Pools Can Cause Burns? 
I recieved a call about someone having burns on their face. They said the doctor told them it's from low calcium levels in a pool. The parameters were …

Large Amounts Of Calcium On Pool Walls 
We have a two month old salt water pool with beadcrete plaster. About 3 weeks ago we noticed a buildup on the polaris that looked like sand particles. …

Fiber Tech Liner 
I had my concrete pool covered with a product called Fiber Tech when it was time for resurfacing. The website talks about calcium levels but says "not …

Calcium In Salt Pool & Mineral Deposits-Hard Well Water Not rated yet
We converted our pool to a salt water system last year after replacing the pool lining and side files. We are very upset that now we are dealing with …

What Is Really High Calcium Hardness In A Pool & Total Hardness Not rated yet
I have just recently started a job to help maintain the swimming pool water. The swimming pool used to be run by the council and they were going to close …

White Calcium Chunks On Bottom Of Pool & Liner Not rated yet
I have a gray bottom pool and in the last two years a white scaly substance (I think Calcium) has taken over the entire pool. You can scrape it off with …

How Do You Remove Stains Due To Calcium Hardness Being Too Low? Not rated yet
While we were away a Good Samaritan neighbor turned the water on into our pool to replace evaporation loss but forgot to turn it off again. The pool overflowed …

High Calcium Hardness Problem Salt Water Pool & Chloride Level Not rated yet
Can you tell me what level I should keep my calcium at in my salt water inground vinyl pool? The text strips say 250-500. I have been told that is …

High Calcium Hardness & Pool Alkalinity... Not rated yet
My test kit came via Endless Pools, but I believe it is the one offered at this website. It looks exactly the same, is made by Taylor i-CARE (K-1005). …

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