The best limescale inhibitor?


An admittedly rather biased look at the types of water ‘conditioners’ and limescale inhibitors available, from the smoke’n’mirrors stuff to what really works. Rule number one is DO NOT buy any limescale inhibitor where the ad/website says “water softener” when it clearly isn’t actually an ion-exchange water softener. That alone tells you everything about the company selling it...that porky pies are evident! You may also be aware that many websites (when you do a search) show ‘Guarantee’ in their blurb. What is their guarantee - is it stated on their website? A particular limescale inhibitor was brought to our attention with their ‘10 year guarantee’...except they don’t tell you what that guarantee is!...


DO NOT BUY a limescale inhibitor unless the makers will give you your money

back - years down the line - if your appliance eventually ‘scales-up’.


Look for this symbol...




Most magnetic water conditioners simply have a mild magnetic field close to the water supply pipe. This is said (by manufacturers of these units) to induce a molecular change to the calcium salts. Such units are reasonably inexpensive, easy to fit, and require no electrical supply. Some types use a very cheap ceramic magnet. However, it is obviously clear that a weak magnetic field would NOT be effective. The magnetic field on passing water would have to be very strong, even extreme.

In our experience, do they work?




An electrolytic ‘water conditioner’ is supposed to work by the use of dissimilar metals placed in the flow of water, being electrically connected. In the presence of water (an electrolyte) a ‘LeClanché’ (battery) cell is achieved. The metals develop an electro-magnetic force between them. This is meant to allow the addition of zinc metal ions in the water which, it is claimed, produces a permanent change to the calcium crystal morphology.


Hard salts are encouraged to cling to each other rather than pipework, heating elements in appliances, etc. It does not require an electrical supply.

In our experience, do they work?




The electronic limescale inhibitor is meant to work by using a high frequency signal generator (0.5 - 100 kHz) which is applied through a direct connection to the pipe surface. The current induces a ‘field effect’ into the water which imparts energy at a molecular level to the water.


As long as the water keeps this energy level, it is supposed to hold a greater amount of salts in suspension and encourage already existing salt deposits to re-dissolve. It requires an electrical supply. There is a company selling these to ignorant architects for an enormous cost - and getting away with it!

In our experience, do they work?



Phosphate & Polyphosphate

Phosphate limescale inhibitors usually require a changeable cartridge with a dosing valve fitted. The idea is that water will flow partly through the unit and thus be dosed with phosphate particles. This is meant to suspend the calcium particles.


Unfortunately, the dosing valve becomes clogged with phosphate very quickly after fitting - thus ceasing any effect the unit may have. We have yet to see a single one that hasn’t blocked itself! These pictures, below, (yet another we’ve removed) tell the story for us. The pics show that the dosing valve is completely blocked with phosphate. When you replace the cartridge, you don’t get to see this view! So you replace the cartridge thinking that it’s still working! It’s wasted money.


No electrical supply required.

In our experience, do they work?



Aqua Conditioners

These use a bed of resin in a chamber about the same size and shape as a scuba-diving oxygen cylinder. It is called nucleation-assisted crystallisation. The idea is that the resin will hold onto the calcium as it passes. When the molecules get saturated with calcium, they get trapped in a post-filter. They are quite expensive for what is a piece of plastic.

In our experience, do they work?




‘Siliphos’ is a widely-trusted food-grade material proven time and again to inhibit limescale formation. Its ability to combat limescale deposits is really quite remarkable, as it both lays down a protective layer on the walls of the supply piping and inhibits future calcium deposits. Because of its ability to provide a protective coating, it’s even suitable for soft water supply pipes - inhibiting corrosion. Siliphos is a food-grade material, and not only is it completely safe to drink, it’s even suitable for babies water. Early Siliphos units (still sold today) are bulky units that have to be topped up every six months and refilled every year. This procedure can result in water leakage. All these negative points were addressed by the introduction of our ‘LimeStop’ range: The CombiBuddy for combi boilers, and the LimeStop Deep Blue for whole-house protection. Siliphos limescale inhibitors do not require an electrical supply.

In our experience, do they work?



Water softeners

A softener simply removes calcium ions, and replaces them with sodium (salt) ones. Such units are expensive to purchase and install. Artificially-softened water must not be supplied to a potable supply, thus possibly creating an installation headache, as a drinking-water supply has to be provided. Softeners are usually bulky units - taking up a whole kitchen cupboard. They require an electrical supply (usually), a drainage pipe, and constant salt replenishment. They are not considered eco-friendly as they require regular (every few days!) back-flushing with copious amounts of water. Annual servicing is also recommended, meaning on-going expense.

In our experience, do they work?




We cannot make this any simpler: Ask the supplier of your limescale inhibitor if you can return the product after six years if your appliance ‘scales-up’. Chances are they’ll just politely tell you that you cannot! So what good is that then? But if in 15, 20 or even 30 years of owning a CombiBuddy or LimeStop, your appliance scales-up, then you could have your original purchase cost back. THAT’S a guarantee that it will work. The LimeStop Deep Blue and the CombiBuddy work, they STOP limescale - dead in the water.



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The CombiBuddy uses silicate-polyphosphate and, is 100% guaranteed to work...or your money back. It is compact, metal-made, and comes with its own isolating valves, and it can be fitted in just a few minutes. It it fitted away from surrounding pipework, yet ‘in-line’. For combi boilers. REPLACEABLE UNIT (from as little as 10p a day!).

£76.00 including postage



LimeStop Deep Blue

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The LimeStop Deep Blue uses silicate-polyphosphate and, again, is 100% guaranteed to work...or your money back. It holds 900 grams of silicate-polyphosphate. It is highly recommended for protecting your whole house against limescale. The LimeStop is located on your mains water supply. For larger applications, two LimeStops (fitted in parallel) can be installed. Bespoke units can also be fabricated for commercial or industrial use. REPLACEABLE UNIT.

£99.00 + postage






If a manufacturer of a limescale inhibitor or water/aqua conditioner won’t promise to give you your money

back in 10 years time if you still get limescale (despite buying and fitting one of their products)...










For independent advice and help on plumbing & heating, click this link -

Just 10p a day

keeps limescale away!