Calcium Hardness a Big Deal?

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2neuges

Well-known member
Jun 26, 2023
56
Paragould, AR
Pool Size
25000
Surface
Vinyl
Chlorine
Liquid Chlorine
We have a vinyl lined, liquid chlorinated pool. When I've had the water tested at the pool store, they begin to freak out when they see a reading of 100. The pool store recommends a minimum of 250 ppm. But my TFP app says anything from 50-650 is normal...should I buy calcium hardness increaser? Or am I ok? Why sich a big range with the TFP method?
Thanks so much!
 
Hello!

The key understanding with calcium in relation to pool surfaces is that water naturally wants to find equilibrium. If your water is low in calcium, it will tend to pull calcium from the pool surface. In the case of plaster or concrete pools, this can cause damage to the surface. However, with vinyl-lined pools, there's no calcium in the vinyl, so there’s nothing for the water to "pull" from.

The reason the TFP method has such a broad range is that for vinyl pools, a vast majority of calcium hardness values work without causing issues. Levels below 50 can increase the chance of metal staining (mainly on fiberglass steps), and very high levels could lead to calcium scaling, but both of these situations are relatively rare, especially in vinyl pools.

In short, there's no need for you to add a calcium hardness increaser in a vinyl pool based on the numbers you've provided. The TFP method is about providing a safe, efficient range that works for most pools without causing unnecessary concern or leading to additional chemical costs.

Hope this clarifies things!
 
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Leebo said:
Hello!

The key understanding with calcium in relation to pool surfaces is that water naturally wants to find equilibrium. If your water is low in calcium, it will tend to pull calcium from the pool surface. In the case of plaster or concrete pools, this can cause damage to the surface. However, with vinyl-lined pools, there's no calcium in the vinyl, so there’s nothing for the water to "pull" from.

The reason the TFP method has such a broad range is that for vinyl pools, a vast majority of calcium hardness values work without causing issues. Levels below 50 can increase the chance of metal staining (mainly on fiberglass steps), and very high levels could lead to calcium scaling, but both of these situations are relatively rare, especially in vinyl pools.

In short, there's no need for you to add a calcium hardness increaser in a vinyl pool based on the numbers you've provided. The TFP method is about providing a safe, efficient range that works for most pools without causing unnecessary concern or leading to additional chemical costs.

Hope this clarifies things!
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Thank you! The pool store's reasoning is that it would begin to pull calcium from my vinyl liner, thus leading to damage of the liner...and obviously I don't want that...and there doesn't seem to be a consensus on the Google about vinyl liners needing calcium or not...
 
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Then we have fillers.

Calcium carbonate is often used as a filler in plastics.

Depending on the amount used in a blend, calcium carbonate can increase the modulus, increase the hardness, and at very high loadings decrease the cost of the formulation.

It was found that at levels less than 7% by weight the physical properties were not significantly affected and that, at levels over 20%, the physical properties were compromised and the chemical resistance severely compromised.

Stanford et al. (1979) showed that high filler loadings resulted in excessive weight gain and, thus, poor chemical resistance.

A PVC formulation incorporating high calcium carbonate amount is by far the most significant negative factor in acidic leachate environments.

When exposed to acidic leachates, and with 37% HCl, formulations with less than 7% calcium carbonate, incorporating a branched or linear phthalate, had less than 5% weight change and – more importantly – were still very flexible.
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www.geomembrane.com

Five PVC Geomembrane Questions | EPI - The Liner Company

André Rollin of Solmers International answers five important questions about functional PVC geomembranes from Geotechnical Fabrics Report.
www.geomembrane.com www.geomembrane.com
 
Fillers:
Fillers are inert inorganic powders whose major role is to reduce costs.

Additions of fillers, especially in high dosages, adversely affect most desirable properties, and therefore are rightly viewed as cheapening agents.

But some properties like Electrical strength and stiffness can improve. Reinforcing fillers like Glass Fibre, Carbon Fibre will not be discussed here.

They are much more expensive than PVC resin and not widely used in PVC formulations.

Non Reinforcing Fillers are a wide ranging group.

For PVC the most important is Calcium Carbonate.

There are two types of Calcium Carbonate which are widely used:

Essential Compounding Chemicals used with PVC Resin, Primary, Secondary Plasticiser, Heat, Light Stabilisers

www.plastemart.com www.plastemart.com

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Precipitated Calcium Carbonate – Multifunctional Additive for PVC

Calcium carbonate is one of the most widely utilized minerals additives in several PVC applications. Ground calcium carbonates (GCC) are used mainly as fillers, while precipitated calcium carbonates (PCC) are multi-functional additives that can function as reinforcing fillers, processing aids and impact modifiers.
Click to expand...

Precipitated Calcium Carbonate – Multifunctional Additive for PVC

Explore the production & functioning of precipitated calcium carbonate as fillers, processing aids and impact modifiers along with its benefits in rigid & plasticized PVC applications.
polymer-additives.specialchem.com polymer-additives.specialchem.com

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Raw Material Make-Up.

There are 3 major ingredients in the chemical makeup of a vinyl liner:

PVC (Poly Vinyl Chloride) is the main building block that goes into creating vinyl liners. PVC makes up 50%-60% of the total raw ingredients.

Plasticizer (petroleum-based oil) is another key ingredient that makes up 35%-40% of the total raw ingredients. This ingredient determines the flexibility of the liner and increases its chemical resistance and life span.

Inert Materials (calcium carbonate – a.k.a. clay) and Stabilizers make up 11%-30% of the total raw material ingredients.
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Athena 20 Mil Above Ground Pool Liner

www.propools.com www.propools.com
 
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Fillers

Flexible pvc compounds have excellent impact resistance.

However, when the end use application will be used under extreme outdoor conditions, fillers are added to perfect surface gloss, mechanical profile properties, color, weathering properties, etc.

Filler types include carbon black, aluminum hydroxide, talcum and calcium carbonate.

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11. A word to the wise on why you should purchase American made – Offshore vinyl is a low cost alternate to domestically produced materials looks and handles very much the same.

However, it is not!

Analysis shows it contains high levels of filler ingredients, calcium carbonate, which adds no value to the vinyl but does make it cheaper to produce.

Essentially, this means, off shore manufacturers are using chalk in place of plasticizers and resins in their vinyl. Calcium carbonate absorbs water easily and can cause the vinyl to expand by as much as 25% (domestic liners only expand 3%) when tested while placed in a low pH environment.

Plus the wrinkles are far more severe in offshore vinyl, as most contain 18%-20% calcium carbonate.

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The manufacturers do not make their own vinyl sheet; they buy it from a supplier.

CGT sells the vinyl sheet material to the swimming pool vinyl liner manufacturers.

The pool liner manufacturers manufacturer the liner from the sheet vinyl.

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In my opinion, there is no need to add calcium to a vinyl liner pool.

The good liners have low levels of calcium carbonate and the water is not going to pull it out as long as the pH is above 7.2.

If you have very low pH, then all vinyl can be damaged.

Cheaper liners can have higher levels of calcium carbonate.

Even for a cheap liner with high levels of calcium carbonate, the calcium level is probably not that important.

Low pH is what causes the most damage to a liner.
 
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If you ever have a warranty claim for a defective liner, then the manufacturer or installer could blame a lack of calcium for the liner failure and deny coverage.

So, that is the biggest issue.

Most people will never make a claim, but if they need to, it can become an issue.

So, you need to take that into consideration.

The manufacturer is not going to care about our opinion if you make a claim for a defective liner; they only care what their warranty statement says.

If it says to maintain a specific level, then that is all they care about.
 
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