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Water softener or anti-limescale filter difference ?

Water softener or anti-limescale filter difference ?

Limescale is a nuisance for both our appliances and our itchy skin. It is also a strain to remove it when it forms patches. So are we really being told the whole truth about the different solutions that exist?

Water softener to anti-limescale filter

There is currently a fierce battle between the salt water softener and the anti-limescale filter. It is sometimes the same manufacturers who offer the different solutions. So what is the difference and what are the constraints of these devices?

In order to understand this, it is important to know that there is no limescale in water! Limescale is in fact the crystalline structure formed by calcium and magnesium ions. These are therefore crystals, which, like stalactites, will only form on a support.

There can only be limestone in water when it has already formed and has been detached from a wall, carried away by the flow of the liquid.

When we talk about hard water, we are actually talking about mineral water that contains a lot of calcium and magnesium. It is these minerals that make up limescale.

Simplistic commercial explanations have led people to believe that limescale can be retained like coffee grounds in a paper filter.

Magnesium and calcium ions

The size of the largest ions is 0.00015 microns! To filter the ions in a filter mass to retain them is impossible, they are much too small!

Filter cartridges are needed!

A filter cartridge is usually placed before water softeners and sometimes integrated with anti-limescale filters. Its role is to retain impurities larger than minerals, below 90 microns. It will technically protect appliances from sand, rust and other deposits that can build up in water heaters and impair the proper functioning of valves, flaps or other taps... These are known as sediment filters and can be supplemented by activated carbon filters.
By forcing the water to pass through a filtering mass with a very fine mesh, it will be possible to retain the coarsest impurities that circulate in the water above 5 microns. However, we will not be able to retain the very fine particles that are dissolved in the water, such as pesticides, heavy metals, but also the famous limestone, composed simply of infinitely small magnesium and calcium ions.

The smaller the filtration fineness, the more the funnel effect will limit the flow and pressure of the water passing through it. This is why it is unthinkable to purify the water of a whole house, you would need huge filters to allow a correct flow.

The activated carbon cartridge will retain the most common dissolved pollutants such as chlorine, pesticides, drug residues etc... it will improve the taste and odour of the water but will not purify it as much as a real water purifier or osmosis machine whose filtration fineness and carbon granulometry are much finer ( ∓0,1 micron).

Backwashable filter

the backwashable filter eliminates the need to replace filter cartridges

How the salt water softener works

As it is difficult to retain minerals through a simple filter, a salt water softener will exchange calcium and magnesium ions with sodium ions through a chemical process. The aim is to remove some of these minerals so that they can no longer crystallize into limescale.

This process will lower "clark degree" of the water. It will therefore make it chemically soft.

The main problem is that people are led to believe that all limescale and minerals will be removed, which is completely false!
If you lower the hardness too much, the water starts to be aggressive to materials and oxidising to metals.
Completely removing limescale will cause leaks and gradually destroy appliances!

fresh water - rust

  • ppm = mg/l = US measure
  • degrees clarks = English degree
  • °all = German degree
  • °f = French degree

Demineralized water is unfit for consumption and should not be drunk or even used for cooking!
The sodium ions that have replaced the minerals make it salty and problematic for your health! (high blood pressure...)

It is therefore strongly recommended to use a salt water softener with a Clark degree higher than 7° and to accept that there are still some traces of limescale.
A separate, untreated cold water supply will be needed for drinking and cooking.

How an anti-limescale filter works

Be aware of the different types of anti-limescale filters!

The common factor between the various quality anti-limescale filters is the sediment filter cartridge.
Remember, this first step will retain most of the impurities that circulate in the water.

sediment filter cartridge
The more advanced models will contain activated carbon cartridges to retain dissolved pollutants.

activated carbon filter cartridge

It is absolutely necessary to avoid chemical products often presented as anti-limescale crystals, which are in fact products based on phosphates, polyphosphates, silicophosphates, etc. This chemical will indeed retain calcium and magnesium ions. But once it is ingested by our body, it will also make it impossible for the body to assimilate minerals! This product is found everywhere in industrial food, we already consume too much of it. Phosphates are not harmless, they can also cause hyperactivity in children... (see our article on this subject)


After passing through the filtering masses, the limestone must be treated, i.e. the calcium and magnesium ions must be treated. It is not a question here of removing or retaining them, but simply of acting on their polarity so that they can no longer, or much less so, crystallise into calcite. The majority of anti-limescale processes thus make it possible to modify the crystallisation of minerals into aragonite. This crystalline form is friable and much more fragile than calcite. As a result, the same advantages as with a salt water softener can be enjoyed while maintaining the intrinsic qualities of the water.

In this range you will find magnetic, electrostatic, galvanic, vortex, electronic and induction anti-limescale products.

anti-limescale models

Non-chemical "anti-limescale filter" systems have the advantage of not causing any corrosion or degradation of the water. On the contrary, it will be of better quality and can be widely used for preparing meals or for filling water carafes.

In order to significantly improve the quality of drinking water, water purifiers and osmosis systems are essential. They avoid the need for plastic bottles and guarantee a much better quality of water. The quality of water also depends on its storage, it is sensitive to light, temperature variations and its container.

The importance of using curative anti-limescale products

Among the "natural anti-limescale" processes that act solely on ionic bonds, there are models that are more effective than others in the long term.

The action on the polarity of the ions and the neutralisation of the formation of limescale crystals generally lasts from 48 to 72 hours.

When the water stagnates beyond its time limit, it regains its properties and can then again start to develop small crystals in very fines layers. However, over time, the formation of limescale will be slowed down considerably, and household appliances, plumbing and boilers, water heaters and taps will be preserved... but it will still be necessary, after a while, to plan maintenance to eliminate the limescale that will reappear.

An anti-limescale system has a preventive purpose and reduces the frequency of maintenance. In normal use and correctly adjusted, it does not have a cleaning role.

So what is the advantage of a curative system?

Contrary to a classic system, the so-called curative processes will act on the limescale already formed during periods of stagnation of the water. They will therefore remove the thin layer of limescale as it reappears. These systems will therefore further reduce the frequency of maintenance. For those who can afford it, the extra investment is well worth the result.

An indicative example of what the different systems could achieve with the same water quality.

Water of identical hardness:

  • without treatment, filter or anti-limescale filter; water heater to be cleaned every 2 years
  • with a magnetic anti-scale filter; water heater to be cleaned every 5 years
  • with a curative anti-limescale filter; water heater to be cleaned every 8 years

In conclusion

Since when is mineral water bad for your health? So let's keep the calcium and magnesium minerals if possible!

With a curative anti-limescale filter system, you will get the same benefits and results as a salt water softener set at less than 7° Clark.

For well-being and health:

  • less limescale deposits
  • softer skin
  • less dry hair
  • softer laundry
  • less frequent descaling of your appliances
  • less aggressive water and still as good
  • easier general maintenance


  • on heating appliances that work better and use less energy
  • less chemicals to be used for cleaning
  • fewer technical problems and plumber's interventions
  • less expenditure on changing household appliances
  • boilers and heat pumps that last longer
  • thermodynamic or conventional water heaters that no longer fill up with sludge and limescale

Apart from changing the filter cartridges that are placed before any anti-limescale system, anti-limescale filters do not require as much maintenance as salt water softeners.

For those who have opted for a salt water softener, remember not to lower the hardness too much, in return, with the almost total elimination of limescale, you will cause other problems of corrosion and disintegration of the materials in contact with this salty, aggressive and corrosive water.

The disadvantages of salt water softeners are:

  • consume a lot of water to rinse the resins and remove the minerals that have been retained to regenerate
  • having to regularly refill the salt tank and clean it to prevent the growth of bacteria
  • having to monitor the valves to avoid water leaks or excessive consumption.
  • not being able to operate without electricity
  • take up a lot of space
  • do not prevent the Clark degree from being lowered below 7°.
  • make the water unfit for consumption
Posted on 2023-05-05 by Fred. Drinking water supply 0 8299

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