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In order to enjoy not only the ecosystem of your garden, but also your pool for a long time, the substrate should be prepared accordingly before installing the pool.

Why is pool substrate preparation so important?

There are a few reasons why it makes sense to prepare the ground appropriately. One of them is the condition of the underlying green area, if the pool is not placed on tiles or a similar solid surface.

In this case, it is necessary to avoid the formation of mold on the turf, as this can lead to an unpleasant odor and, on top of that, negatively affect the garden as a whole.

Depending on the particular model, a pool filled with water may also be very heavy, with 30 tons of total weight not uncommon. Just as the weight of the pool can affect the material of the substrate, that, of course, affects the pool.

More than a one percent slope of the ground, at best, leads to deformation of the pool or, at worst, it tips over when filled with water, which can cause damage.

4 steps to prepare the ground for the installation pool

In order not to expose both the respective pool and the already prevailing conditions in your garden to unnecessary stress, it is recommended to adequately prepare the ground, whereby a distinction should be made between a conventional above-ground pool and a frame pool. In the following sections, you will find the relevant steps explained so that you are best prepared for the swimming season.

Step 1: Acquire the necessary equipment

In the first step, it is advisable to either buy all the necessary items for preparing the ground or, if they are already available, check their condition to ensure optimal functionality.

Before starting the actual preparation measures, it is worthwhile to position the respective tools within reach. This will make it much easier for you to carry out the work and save time.

  • Spirit level: This item is used to measure the area where the pool will be installed. A spirit level is especially useful for detecting as well as correcting differences in height. It ensures one hundred percent straight alignment.
  • Spade: A spade is essential so that you can remove or cut out the existing substrate, for example, in the form of a lawn.
  • Quartz sand: After using a spade, the respective ground is usually more even, but still has a certain amount of unevenness. These are repaired with the help of quartz sand.
  • Grit (for frame pools): For frame pools, you should also have bought enough chippings, because these are also used in the corresponding models, similar to quartz sand to level out uneven areas.
  • Protective fleece/weed fleece (for inflatable pools): To prevent damage from growing weeds, you need a protective fleece. Often this is also known as weed fleece.
Preen 2464107 24-63798 Weed
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  • Pool carpet pad: A pool carpet pad protects the surface of your pool from damage caused by the friction of the material on the ground, among other things, and promises additional stability or support. Usually, it is laid out over the weed fleece.
Boat Decking EVA Teak Decking
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Step 2: Measure and mark the pool substrate

Depending on the shape of the pool, there are different methods to determine the pool substrate, and in both cases the area should be marked with the help of larger objects such as stones.

A square pool is easy to measure, but the outline in terms of length as well as width should allow for a little leeway, and therefore add a few units of measurement in addition.

Setting up a pool, the shape of which is round, is done by using a pipe and a string, the length of which corresponds to the radius of the pool. This is attached to the centrally placed pipe and serves as a measurement in the stretched state.

Furthermore, it is strongly recommended to also measure differences in height. You will need a spirit level fixed to a straight board or post and make sure that if the ground is grass, it is mowed.

It is advisable to measure the slope at least in two directions that are at right angles to each other, and in the case of a round shape, the center can serve as a guide, although some intermediate measurements are worthwhile.

Step 3: Straighten the pool surface

Although some pool models can compensate for minor unevenness for some time, in principle, all of them should not be used in the case of a substrate that has a difference in height of more than three centimeters. There are a variety of options on how to straighten the ground before you can put your pool on it.

Backfilling uneven areas using, for example, silica sand, screened gravel, or garden soil is not very time-consuming, but it does run the risk of causing the ground to shift again.

The safest position for your pool is achieved by completely removing the top layer of soil or the turf using a spirit level. If only the smallest unevenness is involved, the pool can also be dug in at the appropriate places, so that a straightened subsoil is created as a result.

Step 4: Pool substrate Styrodur (XPS) – recommended

Not mandatory, but ecologically very sensible, is to insulate a pool adequately. Depending on the model, either only the bottom is insulated, or the walls must also be included, which causes a constant water temperature with a corresponding energy saving. Styrodur as a material has the advantage that it is stable even under greater pressure and is not sensitive to water.

Prepare pool substrate for frame pool

After preparing the substrate for conventional installation pools, as described in the above sections, there are a few more special features to consider with regard to frame pools. In order to have an ideal and safe swimming experience with these as well, you should incorporate the following three steps into your routine as well.

Step 5: Laying the panels

With the help of a straightedge or level, a tape measure, and a plan for the appropriate installation, you can lay sidewalk slabs. These are important for the later pool stands. After finishing the work, you should again straighten the subsoil with a rake.

Step 6: Laying construction protection mats

In this subsequent step, construction protection mats are placed between the slabs set in the previous step. These add to the fun of bathing in that they are more comfortable due to their soft texture. They are more expensive in comparison, but the investment rewards you with a solid foundation for your pool.

Step 7: Laying the tarpaulin

Due to the fact that most construction protection mats contain plasticizers, it is essential to lay another tarp between them and the pool liner. As with other pools, the pool’s foundation is the basis for a relaxing summer, which is why the use of that extra tarp should not be underestimated.

FAQ: Frequently asked questions about the pool substrate answered

What is the best location for a pool?

In principle, above ground pools and frame pools differ from fixed, inground pools by several characteristics in this regard. In addition to the size of the pool, when choosing a location, you should further consider whether a sunny spot is favored, but one that heats up the pool’s water more quickly.
In addition, it is necessary to ensure that there is a water connection for filling, as well as the rest of the garden in the form of, for example, shrubs or grass will not suffer any damage. Ideally, the pool should be built on a tiled or paved surface, so that the lawn is spared, because it will suffer in the long run in any case, even when using a ventilated Euro-pallet construction.

Does the pool surface need to be straightened?

As a non-specific guideline, in principle, it can be stated that a slope of more than one percent should necessarily be straightened, respectively, that any pool should be exposed to less than three centimeters of height difference.
However, with a frame pool, you can more easily respond to potential variations by adjusting the uprights accordingly. In this regard, a pool that does not have a sturdy frame is at risk of damage from even a small unevenness, as it could tip over on one side due to water pressure.

Is gravel or sand more suitable for the pool substrate?

While the use of sand is generally widespread in the garden to even out unevenness, it is less suitable for the pool substrate. Gravel, unlike sand, is not easily washed out by pool or rain water and does not soften, but it is important to use a protective ground sheet to avoid putting unnecessary stress on the pool material. A good alternative to normal gravel is quartz sand.


Depending on whether you choose a permanent pool integrated into the garden or an above-ground pool, the importance of the pool substrate varies. For both conventional above-ground pools and frame pools, it is essential to ensure that the ground is level so that the pool does not tip over due to water pressure, nor is there any avoidable stress on the material.

It is equally important to choose the ground accordingly: Even if the lawn can be aerated with the help of a certain construction, it will be affected in the long run. Ideally, you should remove the soil or turf to ensure the most level ground possible, which you can fill with quartz sand if necessary. These preparations are not only the prerequisite for a long life of your pool, but also the maximum well-being of your garden as a whole ecosystem.

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.