Calcium In A Salt Water Pool


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 too high.



Thanks for the question Pam

Your test strips are incorrect. The best range for calcium when a pool has a salt water generator (SWG) is between 150 - 250ppm. This is mostly for plaster pools.

Calcium Hardness

For a vinyl pool, you can get the calcium down to 100ppm and it will be fine.

If you keep the calcium level to high with a salt cell, it might calcify up. This can burn up the cell. I know this for a fact because before I became the pool operator for the YMCA salt pool in 2008, they went through 2 salt cells within 6 months.

It took me a while to get the calcium under control, but when I did, I only had to clean it once per month and it hasn't burned up since.

Don't allow the calcium hardness to exceed 250ppm. If it does, you'll need to do a partial drain and refill.

To post a reply, or if you have a similar question, you can see your post "Calcium In A Salt Water Pool" on the Q&A page in the "Calcium Hardness" category.

Swimming Pool Questions and Answers

Check back to this post for updates or answers.

Hope this helps and good luck with your pool.


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High Calcium Hardness..From One Issue To Another

by Vince
(Yuma, AZ)

Now I have another problem. I was in the very slow process of lowering my TA when the pool maintenance guy came by. We had contracted with them while we planned to be gone for the Summer but unfortunately are stuck in the desert again this Summer.

Unknown to me, when our pool went belly up last Friday when we were out of town, he added shock. When we came back Saturday to find a green pool, that's when I wrote to you. The pool was almost cleared up when we tested the Phosphorous (sp) yesterday and said it was high and we needed to add an additive.

I've done that and now my water hardness is near 1,000. That USED to be okay. Sorry for the novel but where do I go from here? Thanks in advance.

Thanks for the question Vince

It's no problem in asking questions. Alot of people have pool issues and that's why I put up this site. I just answered this question yesterday from a guy right up the road from you on Phoenix:

Does Putting The Chemical Chlorine In A Salt System Pool Cause Damage?

I wrote about phosphates in these posts:

High Phosphate Levels And Low Chlorine Issue...

Swimming Pool Phosphate Level Over 1000

The short answer would be this for your phosphates and calcium hardness. Phosphates are food for algae and there's many pool supply stores that would love to sell you all kinds of chemicals to reduce them.

Check out this post:

Do You Really Need All These Chemicals For A Pool Or Are They Just Trying To Get Your Money?

One of the better known brands is Phosfree. It runs between $25 - $32 for a 32oz. bottle. About a buck an ounce. An elevated phosphate level is fine to swim in. The chlorine kills the algae, your pool is clean and clear, so what does it matter what the phosphate level is? The above posts go into more detail.

My first year at the Y I saved them close to $5000 by cutting off the Phosfree. A lifeguard was putting 3 bottles a week in the pool. Remember, $32 per bottle X 3 = $96 per week. 52 weeks = $4992.

I said nope, didn't need it, and the pool has passed inspection from the Oregon Board of Health ever since. Concerning the calcium hardness, I know how hard Arizona water is because of my pool route in the Phoenix/Mesa area.

There's no chemical to reduce hardness. The only thing to do is a partial drain and refill.
You may want to call around for a pool water delivery company and see how hard that water is. They may ship it from somewhere else. I know it's a bummer to be stuck in the heat. My parents are there and they said today (June 22, 2011) it was 113 degrees.

But I'm glad you're still there because I get to answer great questions. You can find your post on the Q&A page in the "Calcium Hardness" category and here:

Calcium Hardness

Swimming Pool Questions and Answers

Hope this helps and let me know how it turns out for you.


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Calcium problem

by Julie

We have a large saltwater pool with a hot tub that we heat frequently. We had the pool put in about 2 years ago.

Since the pool's inception, we have had trouble with scaling around the tile line and anywhere the water spills over the stone. We continue to have calcium show up as being low but I am hesitant to add much because of the scaling everywhere. Can you shed some light?

Many thanks for any info you can give me.

Thanks for the question Julie

I've taken care of several pools in Arizona with this issue. They have very hard water there, about 200 - 300ppm, so scaling is an issue.

You can mitigate this by keeping the pH and total alkalinity (TA) in line. With a salt pool you can get away with having the TA a bit lower, down to 60 - 70ppm and keep the pH between 7.4 - 7.6. This is important because it will lessen the effects of the calcium buildup.

I'd like to have your complete chemical readings:

Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper). It makes troubleshooting much easier and I can tell what going on.

Now for getting rid of the scaling around the tile. You have some options and I'll let you decide which one or combination you'd like to try.

First is the least invasive. White vinegar is acidic, not poisonous, and can do a good job. Straight vinegar in a spray bottle, a pumice stone and scouring pad.

Next is Comet spray cleanser, pumice stone and scouring pad.

Bio-Dex Quart Protect-All Supreme or Salt Protect per 20,000 gallons to the pool water. Pour this into the pool and allow for FILTER for 8 - 10 hours.

Sand blasting with glass beads if you can find a good contractor.

Last is the most invasive, but the best. Undiluted muriatic acid in a spray bottle. It fizzes up and will make the rest of the calcium more brittle and easier to scrape. Be sure you wear long sleeves, eye protection, rubber gloves, and a mask. Muriatic acid is one of the most caustic acids and even a couple of drops on your skin can hurt.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Calcium Hardness" category.

Check back to this post for updates or answers.

If you need immediate assistance (within 24 hrs) or for emergency personal assistance, you can make a donation of your choice and I'll answer your questions by phone.

Contact Me


Hope this helps and have a great Summer.


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Calcium Hardness vs. Chloride Level

by Ray Cheng

We add calcium chloride to our swimming pool to maintain the level of calcium hardness at about 250~600ppm.

However, by doing this, the chloride ion level will be in a relatively high, over 1000 ppm.

Is there any major harm from this high chloride level?

And how to deal with it?


Thanks for the question Ray

There are some reasons that having a too high calcium level is bad for your pool, especially if it's a salt pool with a chlorine generator.

High calcium hardness will result in scaling on the pool surfaces, water line, as well as in the pipes, plumbing and filter.

A salt cell will clog up and calcify quickly when the calcium level is too high.

Your levels of 250 - 600ppm are pretty high, in my opinion, much too high.

Not only are you wasting money, but it's not good for the pool nor the swimmers.

You need to get your calcium levels down between 150 - 250ppm. This way, if your pool is plaster, you won't have any pitting and the water's hunger for calcium will be satisfied.

Pitting is when chunks are taken out of the plaster causing unsightly holes.

The only way to reduce hardness in pool water is to do a partial or full drain, refill, and chemicals balance.

Simple math will tell if your calcium is 400ppm, then doing a 1/2 drain and refill will cause the hardness level to drop by 1/2, or 200ppm.

You'll need to know the hardness level of your fill water as well. If the fill water is already at, say 200ppm, then a full drain would be needed.

Hope this helps and have a great swimming season.


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