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In the hot season, big and small bathing enthusiasts look forward not only to the first, but also to the daily jump into the cool water. Due to the fact that its own swimming pool requires specifically adapted care, depending on the location, weather conditions or the behavior of bathers, it can quickly occur the occurrence of undesirable situations, which include, for example, deposits on the walls and bottom of the pool.

The following sections explain not only what causes greasy deposits and whether they are a danger to health, but also how to eliminate or prevent them.

Causes of slippery and greasy pool walls or pool bottom.

The reason for an altered structure of the pool walls as well as bottom can be explained by the presence of algae. An algae infestation usually happens when the corresponding cells attach themselves, for example, to bathing suits, bathing toys or similar objects that have been used in a polluted body of water.

To be able to use a more concrete definition of the cause, the color present is crucial, as yellow, green as well as black algae discolor the water of a pool, making its walls as well as the bottom slippery.

Are slippery or slimy walls in the pool hazardous to health?

Although all three types of algae that might colonize a pool are not risky to human health per se, they do introduce some additional organisms into the pool’s water. In many cases, these are insects or bacteria, which can sometimes have unforeseen or undesirable effects on the human body.

However, a risk that should not be underestimated, especially with regard to smaller children and pets, is that from a certain turbidity you can no longer see them, which in turn poses the risk of silent drowning.

6 tips against greasy walls in the pool

In the best case, you can prevent the emergence of algae in the domestic pool in the sense that no basic cleaning of the walls and bottom will be necessary.

These preventive measures often take very little time with an appropriate routine and contribute significantly to a visually appealing as well as hygienically safe bathing experience. The following sections describe the individual options in more detail.

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Tip 1: Keep an eye on pool chemistry

Among other things, it is essential to keep the chemical composition of the pool water at an ideal level, especially in terms of pH and chlorine. This also includes the use of an algaecide, because contrary to conventional opinion, these are particularly suitable for the prevention and not the fight against algae infestation.

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Tip 2: Clean the pool regularly

Not only chemical pool maintenance contributes to smooth as well as handsome walls, because physical cleaning of the pool walls and bottom also prevent algae from settling too much.

In this regard, the installation of a filtration system is especially recommended, while you can also regularly use a landing net to remove larger debris such as leaves. In some cases, it is also advisable to use a pool vacuum cleaner, which is available in different models with different functions.

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Tip 3: Run the filter pump for 8 to 12 hours a day

Connecting a cartridge or sand filter system is the first step if you want to guarantee an efficient cleaning of the water of a pool in this way. In order to be on the safe side with regard to the presence or spread of algae, the pump of the filter system should be operated for at least 8 to 12 hours a day.

Tip 4: Carry out shock chlorination every 2 weeks

A so-called shock or shock chlorination is the equivalent of a basic cleanup of the home pool. Once it is performed, any forms of foreign organic particles are permanently removed from the pool’s water.

With regard to the specific implementation, it is highly advisable to read the respective instruction manual of the individually used product, as the manufacturers will address the possible peculiarities of the particular substance there.

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Tip 5: Wash and disinfect pool equipment regularly

Due to the fact that algae get into the pool water from outside, it makes sense not only to wash the equipment used for bathing, such as the swimsuit or other bathing accessories, at fixed intervals, but also to subject them to basic disinfection.

This should be especially the case if the pool equipment was previously used in combination with water, the composition of which was unclear or which showed a load of algae.

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Tip 6: Inspect pool walls and bottom for cracks

It is well worth checking the pool floor and walls for cracks at regular intervals and repairing them if necessary. Damage of this kind is not only difficult or impossible to clean, but also provides the ideal environment for algae to proliferate.

Clean the greasy and slippery pool in 6 steps

Even with correctly implemented preventive measures, it can happen that the algae load is too high and the surface becomes greasy or slippery.

In case you have to deal with algae infestation in your pool, the following steps are essential to get the problem under control.

Step 1: Wash and disinfect everything

Due to the fact that the algae probably entered the pool through an external object, you must take care to prevent a new infestation after the following steps. To ensure this, the affected clothing should be disinfected in the washing machine and the corresponding accessories with an adequate detergent.

With regard to particularly unwieldy items, you can leave them in the pool water during the further process, so that they also benefit from the measures explained.

Step 2: Correct the pool chemistry

Apart from the fact that algae are present in the pool in question, it is very likely that an imbalance in the chemical composition of the pool water is sometimes responsible for its proliferation.

After checking with the help of a test kit, especially the alkalinity, pH and chlorine content are important, it is useful to influence deviating measurements so that they approach the ideal value.

For chlorine, the optimum is approximately 3 ppm (parts per million or milligrams per liter), alkalinity should be between 80 to 150 ppm, and the ideal pH value is a number between 7.2 and 7.6.

Step 3: Brush and vacuum everything off

A thorough brushing will clean both the walls and the bottom of the pool from the existing algae, focusing mainly on the areas that are significantly affected by it.

Once the algae in the water have clouded the view to the extent that the water is no longer clear, the existing dirt must be manually vacuumed, which should be repeated several times, alternating with brushing, depending on the severity of the infestation.

Depending on the nature of the individual pool’s components, either harder or softer bristles are appropriate, so if in doubt, seek consultation with a savvy professional.

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Step 4: Perform shock chlorination

In a so-called shock or shock chlorination, the surface as well as the interior of the pool is freed from the ground up from foreign organisms. Depending on the type of algae, the dose must be adjusted accordingly.

In any case, one should make sure that no ordinary chlorine granules are used, but a pool shocker, and that the process is not initiated before nightfall.

Step 5: Filtering, brushing and shocking again

After the filtration system has been in operation for at least eight hours and the pool surfaces have been brushed again, another shock chlorination is needed, where the use of a single dose is sufficient.

Especially in the case of black algae, a sustained as well as thorough cleaning is highly recommended, although the other types can also be stubborn. In case the pool water is still cloudy in the morning after the last shock chlorination, it is advisable to either use a clarifier or to let some time pass until the effect subsides.

Step 6: Clean the filter

When cleaning the filter, under no circumstances should it be rinsed out, as this would allow the algae to return to the pool. Instead, it is preferable to use a filter cleaner according to the enclosed instruction manual.

After re-testing the chemical properties of the pool chemistry, paying particular attention to the chlorine level, and a possible adjustment, swimming in the pool can be enjoyed again.


As soon as the walls or the bottom of a pool is slimy or slippery, respectively, there is an infestation of one of the three types of algae found in pools. By adjusting the chemical properties of the pool water in combination with basic cleaning with the help of chemicals and manual tools, it is possible to effectively eliminate this problem.

In order to avoid the more time-consuming and labor-intensive steps in the fight against algae, there are some preventive measures, such as regular disinfection, which minimize the risk of slippery or greasy surfaces.

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.