High Calcium Hardness

by David Doig
(Hindly Pheonix Wigan)

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 it and knock it down. The local swimming club and volunteers have taken over the running of the pool and are really struggling with costs.


I have my pool plant and water certificates and have done water maintenance for years.

The problem is the pool water hasn't been looked after for quite a long time so now the levels of Alkalinity and calcium hardness are all over.

There is a 25m by 10m pool and a 12m by 5m pool. We have soft water and the alkalinity is around 20. I stopped testing the calcium hardness on the main pool when I used 15 tablets and the pool water was still pink.

I did the same on the small pool and didn't get a result either. I only know the way to drop calcium hardness by dilution. I drained some of the water from the small pool and added some more fresh water and tried the test again. I used 20 tablets which gave me the result of 780 which is way over what we should be.

We are using HTH calcium hypochlorite granular. I have used this before and acceptable levels can go up to a max of 500.

The costs are a real problem for us at the moment just to stay open so we can't really afford to be dumping so much water to get the levels down. With the cost of chemicals, reheating the water etc.

I was wondering how would such high calcium hardness be affecting the water and if there was a way to keep the costs down to rectify the problem.

Any advice would be much appreciated.

Thanx from a struggling volunteer pool that is trying to stay open for the local community.




Thanks for the question David

There's really no cost effective way to reduce the calcium hardness (CH) in a pool. You either need to do a partial or full drain and refill or have good pool water delivered. This is probably not what you wanted to hear.

A high hardness, pretty much anything over 300ppm will either ruin or shorten the life of the heater. The coils will become calcified and stop working. The proper range for CH is 150 - 250ppm.

You must immediately stop using calcium hypo. This is adding calcium to the pool and causing you more harm than good. Use liquid chlorine. This will not raise the hardness like granular chlorine.

You can also get scale formation on the pool surfaces, at the water levels, and scaling in the pipes, plumbing and filter. In some cases the water can become dull and cloudy.

Some people recommend using he problem with the sodium carbonate which is pH Up or Arm & Hammer Super Washing Soda but you can't control where the scale will happen. It will cloud the water.

Then you add a flocculant, allow it to settle, then vacuum to waste. You run the risk of scaling on the pool walls. This is why water replacement is safer and more effective.

I wish I could be more help but a partial drain and refill is really the only way to go.

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.

Donation

Hope this helps and have a great Summer.

Robert





Comment: Thanx for your feedback. I thought it was the only way to go but was worth a try asking.

We are using a granidos system to feed the chlorine and acid together so we arnt set up to use liquid chlorine.

Thanx again for your help

Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Calcium Hardness.

What Is Calcium Hardness In A Pool?

Please explain what "hardness" means and how do I treat it.

Are special chemicals needed?

How important is it?




Thanks for the question

I'd first direct your attention to this page:

Calcium Hardness

It goes into much detail about calcium hardness, what it is and does.

The short answer is hardness of pool water is the total mineral content of the water.

This is made up of elements like calcium, magnesium, copper, iron, manganese and others.

The ideal range for the hardness is 150 - 250 ppm.

If the calcium hardness is too low, the water can become corrosive. This can result in etching of the pool's surfaces.

It can also cause pitting of the plaster pool.

This is where chunks are taken out of the plaster because water is hungry for calcium and will take it wherever it can get it.

If it's too high, scaling can happen and the filter, heater, and pipes become clogged.

There's no chemical to reduce calcium hardness.

A partial or full drain is required with water that has less hardness.

Sometimes a pool delivery company could be called in. They have the water already balanced out and ready to go.

Pool Water Delivery

Hope this answers your question and have a great Summer.

Robert

Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Calcium Hardness.

Rasing Total Hardness In Pool Water

by Bob
(New York City)

Total hardness of swimming pool water is given in the literature as 250-350 ppm. You mention it should be 150-250ppm.

Here in NY the water is very soft, i.e, 25-75 ppm hardness. What is the best level to go to adding calcium chloride, 150-250 or 250-350?




Thanks for the question Bob

Yes, I say throughout my site that CH should be 150 - 250ppm for plaster pools and at most 100ppm for vinyl pools, and here's why.

The calcium keeps the water from drawing the calcium carbonate from the plaster. When the calcium is not high enough the water will draw the carbonate out of the plaster and cause pitting.

I realize the pool books say to keep the CH a bit higher, and you can, but from personal experience this is unnecessary. There's a point of diminishing return when the CH is up this high. You only want to use enough chemicals to do the job. Any more and you're wasting money.

Salt pool owners need to be concerned about the CH of their pools as well. Again from personal experience, if the CH is allowed to get too high, above 250 - 300ppm the chlorine cell can calcify and burn up.

I've found that by keeping the CH between 150 - 250ppm it will satisfy the pools requirement for hardness but not too high that it will harm chlorine generators. This is the nice middle ground for both.

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

Donation

Hope this helps and have a great Summer.

Robert

Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Calcium Hardness.

Really High Calcium Hardness

by Sharee
(South Australia)

We have just bought a house with an above ground 38,000 litre pool. It is chlorine not salt.

All our levels read fine except our calcium hardness is between 350-420 weekly (we take it to our local pool testing shop each week and they test it for us through their computer system).

No one seems to know why it is this high and we have added calcium products and nothing has helped.

Everyone with chlorine above ground pools in the area apparently had high calcium hardness readings and we have been told not to worry about it.

Our pH is 7.2 and our chlorine is 7 which I'm told is all ok, its just our calcium hardness that keeps reading high.




Thanks for the question Sharee

Unfortunately there's no fast and effective way of reducing calcium hardness but here are some things to consider.

What is the hardness of the fill water? If it's high then you may consider having your pool water delivered if you have that option.

Next, I'd ask what "calcium products" have you added to the pool? Is this to reduce the hardness? You really need to be careful when adding any extra chemicals because they can cause other problems later on.

Are you using calcium hypochorite (granular) to chlorinate you pool? If you are you need to stop and use liquid chlorine. By using cal hypo you're adding more hardness to the water.

Check the ingredients on everything you put in the pool. You may be surprised at what adds hardness to the water.

The 350 - 420ppm range isn't optimal, but it's not the worst. If you do all of the above and still have high hardness, one thing you can control is the pH. Keep it a bit low, between 7.2 - 7.4. This will help soften the hardness a bit and lessen the chances of a white ring around the water line and calcification of the plumbing.

I hope this has answered your question to your satisfaction.

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 feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of $35 per hour and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.









Hope this helps and have a great Summer.

Robert

Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Calcium Hardness.

Hardness vs. No Hardness

by Bob Brewer
(Grass Valley Ca. )

Above ground pool. No metal parts contacting pool water.

But plan to add chlorine generator. Hardness test, indicator shows no hardness present- sample does not show any redness. In this case I did not add hardness titrant.

The water feels soft and simply great no eye redness or skin irritations.. water is clear.

I would need to add 40 to 50 lbs of calcium choride to reach 100 ppm. Perhaps double to reach minium of 200ppm.

BTW - the water went through a pellet iron removal filter otherwise the pool water would be red/brown. What harm would there be to keep the hardness low in this case? CYA is 60ppm.




Thanks for the question Bob

For visitors that may not know, I'll go over a few things first.

Hardness is mainly for plaster pools. It's main function is to keep calcium carbonate from leeching into the pool from the plaster and grouting.

When the calcium hardness is too low the water will draw calcium carbonate from the plaster and cause pitting. By adding calcium chloride you will, in effect, satisfy the water's hunger for calcium.

Since above ground pools are plastic or have vinyl liners, and there's no calcium carbonate, there's no real reason to add calcium chloride. Some vinyl pool proponents will tell you to add calcium because it keeps the liner flexible and soft.

I'm not totally convinced this is 100% true. There's alot of misinformation concerning pools, such as using an algaecide to kill algae. An algaecide is used for preventative maintenance, not to kill existing algae.

Adding calcium and bringing the hardness level up to 100ppm won't hurt your pool. Even 80ppm would be alright. Personally I wouldn't go higher than that due to the reasons stated above and the fact that you're going to be adding a chlorine generator. A hardness that's too high, above 250ppm, can calcify the cell and burn it up.

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

Donation

Hope this helps.

Robert

Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Calcium Hardness.

Calcium Ring Video

by Candace

I watched a video in which you made a gooey concoction of muriatic acid and something else to remove the calcium ring from my pool.

Now I can't find the video.

Could you tell me again what it was?

Thanks!

Candace





Thanks for the question Candace

That wasn't my video but I know what product you're referring to and what to use. It's called Gysar "F" Tile Brite.

You mix this in a 2:1 ratio with muriatic acid. Let it sit for about 24 hours. It'll thicken up nicely. Liberally apply it to the tile and use the pumice stone.

Next is Arrow Scale Off Concentrated Tile Cleaner. It's a bit less effective than the Gysar but safer due to not needing to use acid. Use it straight from the bottle.

Remember to not use calcium hypochlorite (granular chlorine) in your pool.

My pool route was in the Mesa/Tempe area and I know the water is very hard. Only use liquid chlorine.

I hope this has answered your question to your satisfaction.

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 feel your situation is more complex and want immediate assistance (within 24 hrs) you can make a donation of $29 per hour and I'll answer your questions by phone.

Have I helped you find a solution to your pool problems? Did this information help you? Please consider making a donation to help keep this site going. Thank you.









Hope this helps and have a great Summer.

Robert

Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Calcium Hardness.

swimming pool care, basic pool care, above ground pool maintenance, inground, salt water

Click Here To Learn How This eBook Can Save You TONS Of Time & Money

Click Here To Learn The Best Way To Clear Up Your Pool 

Recent Articles

  1. Rusty Iron Bolt Stain

    I have a dark brown iron stain from a rusty bolt that the kids threw in my cement pool.

    Read More

  2. How Long Does Can We Swim After Adding Muriatic Acid To Lower The pH Level?

    We added muriatic acid to our pool to lower the swimming pool pH level. I need to know how long after we added it to swim. Thanks for your question James

    Read More

  3. Foam In The Water..Swimming Pool..How To Get Rid Of..

    We have a 20x40 kidney shaped gunite pool. It was backed washed yesterday and some DE added. Pool water tested o.k. but towards the evening bubbly or

    Read More