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Many people associate a carefree summer’s day with extensive romping or relaxing in the crystal-clear water of their own backyard pool.

However, if unsightly white or white-grey discolorations form on the edges of the pool, limescale has probably set in and is threatening to upset the enjoyment of bathing.

In this case, it is worthwhile to remove the limestone and then take preventive measures so that it does not return.

In the following sections, we will discuss, among other things, how limescale occurs, why it should be removed, and what steps can be taken in this regard.

What is limescale, and why should limestone deposits be removed from the pool?

Limescale (or calcium scale), which is also referred to as lime in a variety of cases, is often, but not always, a result of water that is too hard. Limestone deposits, for example, can be recognized by their hard cream-colored consistency, which has a high chalk content.

In principle, a distinction must be made between two types of calcium deposits, because on the one hand it could be calcium carbonate, but on the other hand it could also be calcium silicate, which should be removed in different ways.

A lime deposit often appears visually as a white foam on the waterline, but if it is not removed, it will solidify, making it much more difficult to treat.

Due to the fact that limescale can cause irreparable or costly damage to the pool filter, piping system, pool ladder, grout, and numerous other materials, it is highly recommended to remove any type of limescale buildup from the pool.

Apart from clogging of the filter and the corresponding pipes, as well as erosion of numerous components, untreated limescale deposits also create stains that permanently affect the overall appearance of the pool.

How do limescale deposits form in the pool?

The deposition of limescale is usually due to an interplay of a number of factors, including an excessively high calcium hardness value. This is caused by excessive alkalinity in combination with an increased pH value, whereby the latter plays a significant role in lime deposits in the pool.

A pH significantly above the ideal range favors the so-called scale formation, in which calcium solidifies and subsequently accumulates as lime on the surfaces of the pool in question.

Furthermore, it is possible that limescale build-up occurs when the water filled into the pool evaporates, which becomes noticeable through rims or discoloration on the respective water line.

Removing lime deposits in the pool in 8 steps (instructions)

Especially if lime has already solidified on the surfaces of the pool, removal is usually very lengthy or complicated in numerous cases.

The following steps can be used to remove smaller areas of lime scale, as well as more extensive lime scale deposits.

Afterwards, nothing stands in the way of a carefree summer bathing experience for young and old bathing enthusiasts.

Step 1: Get the necessary accessories

To ensure that the subsequent steps can be carried out smoothly and promptly, it makes sense to purchase all the materials needed to remove limescale from the pool in advance or, if they are available, to check that they work properly.

In addition to a pool brush, a pool tester and liquid reagents, a putty knife, a surface cleaner or limestone remover and a pumice stone or a hand brush with stiff bristles are necessary.

Step 2: Test pool water

Due to the fact that the deposition of lime is in most cases caused by a not ideally adjusted composition of the pool water, it is recommended to check the respective composition.

For this purpose, the pH value as well as the alkalinity and the concentration of calcium in the pool water are determined with the help of an appropriate test kit, so that these can be regulated if necessary.

Get reliable test results with this digital pool water tester:

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Step 3: Reduce the calcium level in the pool

In order to bring about a reduction in the calcium contained in the pool water, it is necessary that the pool be partially drained.

An increased calcium content not only promotes the deposition of lime, but also sometimes results in a turbidity of the pool water, so that the respective ideal value should be between 200 and 400 ppm (parts per million) or milligrams per liter.

The pool can then be refilled with fresh water.

Step 4: Adjust alkalinity

After the concentration of calcium has been lowered and the pool water has been renewed, it is necessary to measure the alkalinity of the pool in question and, if the value is not optimal, to adjust it accordingly.

Once the water has been tested again for its properties after a reasonable period of time, the alkalinity should be many times lower in that particular case.

Especially when the hot summer months reach their zenith, it is also advisable to set the level of the disinfecting chemical chlorine to a value between 2 and 3 ppm (parts per million), or milligrams per liter.

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Step 5: Adjust pH value in the pool

Due to the fact that an incorrectly measured pH has a very strong effect on the formation of limestone on the surfaces of the pool, it is essential to settle it in an ideal range. An alkaline pH means that the water contained in the pool is supersaturated, which in a large number of cases manifests itself as calcium deposits.

In order to restore the optimal water balance, it is necessary to lower the pH value to the ideal range of 7.0 to 7.6 with the help of acid.

In case of doubt, the dosage of the appropriate pH reducer should be done according to the individual manufacturer’s instructions, which are contained in the enclosed instruction manual, and the agent should then be added directly to the water at several points when the pump is in operation.

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Once a retest indicates an ideal value after a twelve-hour waiting period, you can now efficiently move on to removing the lime.

Step 6: Determine the type of lime deposit

In order to achieve lasting success in the removal of the accumulated limescale, it is essential to define the respective type of limescale deposit in a first step. Depending on what it is, there are different established methods for removing the corresponding change formed by lime on the surfaces of the swimming pool.

Calcium carbonate: In this case, there is a variant of limestone that is, in principle, easier to remove, which manifests itself in the formation of flaky, white pebbles.

If one is unsure whether the assignment of the visible properties fits this type, it is a good idea to add a few drops of muriatic acid, also known as hydrochloric acid, to a sample taken, as a foaming reaction confirms the presence of calcium carbonate.

Calcium silicate: Assuming no foaming occurs when testing a sample, calcium silicate is present. It is much more difficult to remove and has a white-greyish color.

Due to the fact that the formation of this type of calcium silicate requires a longer period of time, there may also be calcium silicate deposits in the filter system of the individual pool or in the corresponding pipes, for the removal of which professional assistance is strongly recommended.

Step 7: Take precautions

Both to avert superficial irritation of the skin, for example, in response to a limescale remover, and to avert deeper physical injury, adequate protective gear should be donned before the particular limescale is removed.

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Depending on what materials are part of the corresponding pool, respectively what individual characteristics the applied accessories require, among other things, further steps may be necessary.

For this reason, it is essential to consult the respective operating instructions before removing limescale and, in case of doubt, to seek personal exchange with a specialist or with experienced pool owners.

Step 8: Remove limescale from the pool

Once the appropriate precautions, adapted to the situation on site, have been taken and the type of limestone present has been determined, different characteristics must be taken into account when removing calcium carbonate or calcium silicate. The following sections describe each step in detail.

Removing calcium carbonate deposits: in order to remove this type of calcium deposit, either a pumice stone, used for manual removal, can be used exclusively on hard as well as wet surfaces, or a conventional stain remover, which, according to the manufacturer’s information, also removes calcium carbonate when used properly.

An equally professional alternative, which is also equally suitable for all surfaces, is a specific lime remover, which takes effect over a period of several weeks in the water of the pool.

Removing calcium silicate deposits: Provided that the pool is not a fiberglass or vinyl pool, a pumice stone can be used to remove calcium silicate in a very labor-intensive operation.

While a pumice-specific additional substance can also remove the calcium silicate deposits, it is not uncommon for the dissolution process to extend over several months.

Assuming that, for example, because you have a vinyl or fiberglass pool that would be scratched by pumice, you cannot use it, coordinated products from a professional provider of pool supplies are necessary.

Remove lime deposits in the natural pool with citric acid (instructions).

In addition, for a natural pool, the dissolution of lime into the individual components oxygen, carbon and calcium with the help of the home remedy citric acid is also an option.

In most cases, however, the citric acid is added in the form of granules, whereby approximately 200 to 400 grams per square meter of pool surface should be used. However, it is recommended to always adjust these specifications to the individual situation on site in the home garden.

In order to efficiently remove any lime deposits from the natural pool, fine socks filled with the granulate and weighted down with a stone are placed in the water of the pool at regular intervals, whereby the pool water must not be moved either by external influences, such as wind, or by internal influences, such as the use of a telescopic pole.

After a nightly exposure period, the empty bags are removed from the natural pool the following day with the help of a landing net.

If the water is circulated by the pump and a pool robot is used for appropriate cleaning, lime deposits should no longer be present.

Removing lime deposits from tiles (instructions)

If you want to remove limescale from the pool tiles, the first step should be to lower the water level with the help of a garden hose.

Then, first, it is recommended to spray white vinegar on a small part of the surface to be treated, let it act for 20 seconds and then remove the lime with a scrubbing brush.

In the event that this procedure does not work, acid cleaning or acid washing is necessary.

The first step in an acid wash is to mix one part acid with three parts water in a 20 liter bucket and then pour it into a watering can or something similar so that the mixture can be spread over the lime deposits.

Afterwards, the limescale can be removed with a spatula, a pumice stone or a pool brush, for example.

Due to the fact that there may be harmful fumes when the acid wash is applied to a lime deposit, it is sometimes recommended to seek the advice of a professional in order to adequately prevent potential risks.

Removing lime deposits on plaster (instructions)

If you want to remove limestone that has settled on plaster, you should first of all use a pumice stone, as this often already efficiently removes the calcium present in crystalline form.

However, acid cleaning in conjunction with the subsequent use of a pumice stone may also be necessary in this case. It should also be noted that plaster, due to its material properties, is not so easily damaged, which means that sometimes, in the case of stubborn lime deposits, the prudent use of a wire brush may be possible.

Preventing limescale in the pool: here’s how

There are several ways to prevent the formation of limescale, which often involves time-consuming as well as labor-intensive removal.

On the one hand, it is helpful to brush the pool at regular intervals and then use a pool vacuum to suck up any loose calcium particles.

On the other hand, it can happen that these are too small in size, so that they must first be bound by the administration of a flocculant, which makes them tangible for the vacuum cleaner of your pool or filterable for the respective filter system.

In addition, the individual pool chemistry should be checked regularly and the specific properties of the pool water should be adjusted accordingly in case of deviating, non-optimal values.

An ideal pH value is usually between 7.0 and 7.6, and the best possible alkalinity is 80 to 90 ppm (parts per million) or milligrams per liter. If you are confronted with the formation of limestone more often than average, the addition of calcium hypochlorite, for example, is strongly discouraged.

Conclusion

The deposition of lime or limestone on the surfaces of your swimming pool is not only visually striking, but can also have some negative consequences if the filter or raw system is affected.

Due to the fact that the removal of lime deposits is very tedious as well as labor-intensive, although not impossible and conceivable through a variety of options, it is advisable to take preventive measures so that a lime deposit does not occur in the first place.

With regard to the respective steps to be taken, an efficient routine is quickly established in many cases, so that the most time can be devoted to the carefree bathing pleasure.

Larry has been a true water rat since childhood. Pure pleasure turned into a passion. That's why he is the first point of contact for friends and acquaintances when it comes to pool-related problems. He is an integral part of the PoolHandbook editorial team.