Calcium hardness and vinyl liners

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tmpfeifer

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Jun 20, 2009
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I just took a water sample to the pool store so that I could use the results to improve my test color interpretation skills. The store measured my calcium hardness at 150 and recommended I add hardener. As I had learned on this wonderful site, I replied that since I have an above ground pool with a vinyl liner this was not an issue and I was happy with the 150 level. The answer to this was that the ideal calcium hardness doesn't entirely have to do with the pool surface, it's about what the water "needs". The salesperson said that the water needs calcium and if it doesn't have enough it will acquire it, suggesting that the water would leech it from the swimmers. I actually had to hold back a laugh. I wish at the time it had occurred to me to point out that to protect her bones perhaps she should never take another shower.

So my question... Am I understandig this site correctly, there is no need to tend calcium hardness in vinyl pools? Is there any consideration beyond pool surface that applies to maintaining calcium hardness?

As always, thanks for all the insight!

Therese
Above ground 24' 13,500gal

TH 150
FC 5
pH 7.8
TA 80 --> working on it with pool calculator
CYA 50
 
In a vinyl pool you don't have to worry about low CH only high. The only reason to worry about it would be if you had a piece of equipment that the warranty hinged on the CH being maintained at some level.
 
I, too, have ignored my "0" CH readings. My neighbor was taking her pool water to be sampled (I do my own sampling) and offered to take mine with her. I was curious as to how my results would compare and sent the sample with her. None of the results or recommendations surprised me but they suggested adding 80# of Calcium Chloride Flake to raise my CH to their recommended 174-350ppm range. When I told my neighbor that CH isn't a necessity in a vinyl pool, she said it helps to stabilize the other chemicals and has helped her keep her pool looking good.

Any thoughts on this? BS? Fact? Fiction? Old wive's tale?
 
CH does not stabilize other chemicals and is not needed to make a pool look good. Too low a CH can have a pool have more foaming, but usually it's a spa where this is an issue since there is far more aeration. Around 120-150 ppm CH helps to eliminate foaming in a spa, but is not usually needed in a pool.

Calcium is only needed in a pool or spa when one is trying to saturate the water with calcium carbonate -- that is, adjusting pH, TA, CH (and temp and CYA) to have a zero saturation index -- for the purpose of preventing calcium carbonate from dissolving from plaster surfaces and grout between tile. If there is no calcium carbonate in a surface exposed to the water, then there is no need for such calcium carbonate saturation. It's as simple as that.
 
Thank you so much for this great advice. I've gotten so tired of adding Calcium Hardness Up to our 24,000 gallon vinyl pool that I'm about to pull my hair out. And at 55 years old, I don't have much left. Thank you, thank you, thank you.
 
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Oh wow, I was just about to buy calcium carb for my vinyl pool. Thanks for the heads up here. My pool is four years old and nobody ever measured total hardness until now. It is at 75 ppm.
I read above that I only have to add calcium carb to a vinyl lined pool IF there is equipment that can be hurt by low hardness. Does a salt water generator count? Will my Hayward t- cell-15 be hurt by low hardness?
thank you to any and all who reply...
 
Welcome to the forum! :handshake:

Only item normally viewed as needing a CH higher than 50 ppm or so with a vinyl liner pool is a heater. And that is only to satisfy a warranty. Most heater manufacturers use an old boiler standard that showed needing hardness in the water. A pool heater is no commercial boiler.

If you are interested in learning about TFPC, I suggest you read Pool School - ABCs of Pool Water Chemistry and consider reviewing the entire Trouble Free Pool School book.
 
Thank you for giving of your time to help on this forum. I have read ABC’s of PC and the sections on calcium in the Pool School ebook. I am confused because the app lists 175 ppm as a target range for my vinyl pool and suggests I add calcium. Please advise. Thank you.
 

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I tend to disagree with comments about Hardness in vinyl pools. I think its wise to use the langelier index of balanced water. I worked in a water park on the east coast and if I added Calcium on my partners weekend he knew just by looking at the wateron Monday that it was clearer. You don't have to take my word just try it yourself. The harder the water the more the sun sparkles off of it. I don't worry about it at my home pool but I get up to 250 or 300 and it stays there depending on rain. I think for the cost it's worth it. If you do add calcium chloride be sure to mix it well in a bucket with lots of water and something to stir it because it gets hot.Plenty of water. Just my opinion.
 
Jill in MS said:
Thank you for giving of your time to help on this forum. I have read ABC’s of PC and the sections on calcium in the Pool School ebook. I am confused because the app lists 175 ppm as a target range for my vinyl pool and suggests I add calcium. Please advise. Thank you.
Click to expand...

I can understand. CH in a vinyl pool is not necessary chemically but a range is placed in the recommended levels to satisfy heater manufacturer warranties. The ranges in the app are suggestions. You should research them more and ask questions to narrow them to your specific situation.
 
Thank you for sharing your experience. We added app’s suggested amounts of bleach and CYA yesterday, let pump run all the while, and vacuumed this morning. We then went on and added the app’s recommended dose of calcium chloride and the water does look sparklier. Not sure what did it, but water looks and feels lovely. : )
 
Thom53us said:
I tend to disagree with comments about Hardness in vinyl pools. I think its wise to use the langelier index of balanced water. I worked in a water park on the east coast and if I added Calcium on my partners weekend he knew just by looking at the wateron Monday that it was clearer. You don't have to take my word just try it yourself. The harder the water the more the sun sparkles off of it. I don't worry about it at my home pool but I get up to 250 or 300 and it stays there depending on rain. I think for the cost it's worth it. If you do add calcium chloride be sure to mix it well in a bucket with lots of water and something to stir it because it gets hot.Plenty of water. Just my opinion.
Click to expand...
Thank you for the sparkling water tip. I added calcium & think it may have made our water sparklier, too. : )

- - - Updated - - -

mknauss said:
Be sure you test FC and add the bleach EVERY DAY.

Take care.
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Plan to! Thanks again!
 
The raw goods used to make sheet material have changed over the last 10 years. The changes were made to comply with environmental regulations & more recently cost saving measures.

It is wise to keep liner pool calcium around the 200 mark.
 
PoolguyinCT said:
The raw goods used to make sheet material have changed over the last 10 years. The changes were made to comply with environmental regulations & more recently cost saving measures.

It is wise to keep liner pool calcium around the 200 mark.
Click to expand...

Are there any articles that back that last statement up?

At least a few times a month vinyl pool owners are advised to not care about calcium levels.
If what you say is true, then it would be a good start to preaching that.

When I had my new liner installed 2 years ago they said nothing in spoken word or
in the documentation to maintain CH levels. Just keep the ph in line.
 
borjis said:
Are there any articles that back that last statement up?

At least a few times a month vinyl pool owners are advised to not care about calcium levels.
If what you say is true, then it would be a good start to preaching that.

When I had my new liner installed 2 years ago they said nothing in spoken word or
in the documentation to maintain CH levels. Just keep the ph in line.
Click to expand...

White papers & IMT are only being funded now. My comments about 2 years out, so you will have to wait if you need 3rd party disclosures.

Tara Corporation has made some murmurs on their blog, you can find them.

I have mentioned it here several times & was met with contention.

Cal is cheap, replacement liners are not.

There is subpar, sheet material in mainstream distribution. Just like the whole Chinese drywall fiasco, fillers used to curb manufacturing costs.
 

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