Calcium Hardness & Swimming Pool Chemistry

Swimming Pool Care

Anything more is not good swimming pool care and pool water chemistry.

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 pool and chemistry problems.

Keep your calcium hardness level between 150ppm-250ppm will prevent this from happening and help with your pool water chemistry. Some areas of the country may have very soft or very hard water.

You need not 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.

Here in central Oregon we have very soft water, about 1ppm-2ppm. In places like Arizona, Nevada, and Southern California the hardness may reach 200ppm-300ppm or higher.

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.

Take the time to understand the best pool tips for your swimming pool.

But My Pool Guy Said This...

Most information you’ll receive about swimming pool water chemistry will tell you to maintain your calcium hardness at higher levels. This is based upon the "Langelier Index", which is used for public water systems and not specifically designed for swimming pool maintenance or Hot Tub maintenance.

This index has been around for a long time, before swimming pools and hot tubs were readily available to the public. There is a better way to handle your pool chemicals and pool chemistry.

Problems With Low Calcium Hardness:

1. Pitting and etching of the plaster
2. Dissolved grout in your pool
3. Staining of the pool surface
4. Possible heater failure
5. Corrosive and scaling water

Problems With High Calcium Hardness:

1. Skin and eye irritation
2. Cloudy water
3. Clogged pool filters
4. Poor filtration
5. Calcium build-up and corrosion on heaters
6. Scaling of the pool water

What’s The Hardness Of Your Tap Water?

When you have softer water, you may need to add Calcium Chloride to feed your pool water’s appetite for calcium. DO NOT make slurry or mix the calcium chloride in a bucket with water. It may “steam” up and cause severe burns.

I had to add calcium chloride into the pool at the YMCA, and being the great pool operator that I am, decided the best thing to do is to mix the calcium with water. Did this once, and only once. Remember the first time you stuck a paper-clip in a light socket? Kinda like that. In about 10 seconds my hand turned a bright red and started to burn. In about 30 seconds I realized the 2nd degree burns on my hands.

So take a fool's advice and don't make a slurry with calcium chloride. Breathing the fumes may be hazardous as well.

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 cell. 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 chart to see the amount calcium chloride your pool needs for proper pool water maintenance.

Hard Water And High Calcium Fill Water

Having high calcium hardness (above 250-300ppm) in your tap water is very hard to keep down. Reducing calcium hardness is a bit more difficult. You may either replace some or all of your pool water or add chemicals, water softening or a Metal Sequestering Agent, that will reduce your water hardness. If your swimming pool problem persists consult your pool professional.

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.

Unfortunately there is no quick and easy answer on lowering the calcium hardness of your swimming pool water.

Remember what I said, it’s easier to add chemicals than it is to get rid of them. This is one such case.

When your fill water has elevated levels of minerals it can be troublesome to keep your pool’s calcium hardness at its proper level.

Chart - Raising Hardness With Calcium Chloride

Pool Water Testing For Calcium Hardness:

1. 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.
2. 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.
3. 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.
4. Why should I test for hardness?
Water hardness is one of the four elements that make up the test routine. Included in this are chlorine, 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.

Put the Tylenol away.

Go swim and have fun with your family and friends.

Go To:

Pool Tips From Calcium Hardness