Pool Construction DIY – With Counter-Current System

Buy it in winter, dig it out and build it in spring, so you can swim every day from the beginning of summer.

A self-installed, in-ground, concrete, insulated, steel-walled, foil-lined pool will be presented, including the installation of a counter-current system and heat pump pool heating.


Have you ever experienced this?


You can watch the full video on facebook.

You don’t need a large dog for this. It’s enough to have a tired foil inflatable pool, from which air is slowly but steadily escaping, and a curious cat, who, preferably in the middle of the night, presses down the edge of the pool to see what’s inside. Once it does, the edge won’t come back up due to the low air pressure, and by the time you wake up from the sound of the gushing water and rush out, the garden is already ankle-deep in water.

This is when you decide you want a safer solution.

Built-in steel-walled foil-lined pool with insulation and concrete

The choice fell on a steel-walled foil-lined pool, and since the manufacturer suggested that the pool should be at least 30 cm deep in the ground for side stability, we got the idea to dig it in completely. This way, it doesn’t overwhelm the relatively small garden.

The Selected Types:

Steinbach Styriapool round Ø350x120cm


Robust, galvanized steel wall (approx. 0.60mm up to 1.20m depth)
Plastic upper edge and floor rail
Winter-proof foil in Adriatic blue: approx. 0.60mm thick
Skimmer and nozzle perforation
Disassembly in winter is not necessary. The holes punched for the skimmer and inlet nozzles are already available. The “Styria” series round pool is suitable for partial or full in-ground installation. The Skimmer kit S1 is optimal for pool water circulation.
Water capacity: approx. 14,000 l (Filling height 115 cm)

Since the pool has a diameter of only 3.5 meters, it doesn’t offer a sporty swimming opportunity, only a recreational one. Therefore, we considered it essential to install a swimming machine. There are additional external hanging swimming machines, but they would have taken up more space in the small pool and the noise from the high-performance motor would have been right at the pool edge. We definitely wanted to avoid the noise.

Aqua Jet Counter-Current Swimming Machine 3.0HP/400V


High-performance, wall-mounted counter-current system, suitable for all types of swimming pools (plastic, steel-walled, concrete, or polypropylene).
The counter-current system includes a high-performance pump, shut-off valves, installation elements with a mounting kit and front panel, seals, a pneumatic button on the front panel, and the corresponding electrical control box.
Easy to install.
The 40mm diameter nozzle allows for the adjustment of water jet intensity and air mixing. The water jet direction is adjustable.

Pump performance: 70 m3/h
Power: 3.0 HP
Rated power (P2): 2.2 kW
Input power (P1): 2.8 kW
Operating voltage: 400 V
Rated current: 4.9 A/phase
The package includes:
1 wall-mountable element with front panel and pneumatic switch
2 75mm ball valves
1 assembly aid kit, including the air tube and accessories
1 2.2 kW counter-current motor
1 electrical control box with pneumatic switch

Since the property is already equipped with a three-phase power supply, the option for a three-phase electric motor was obvious. With a single-phase motor, one phase would have been used near maximum capacity, which could have caused additional issues with the distribution of the house’s existing electrical equipment.

The sand filter was already available from last year:

T.I.P. SPF 180 E Pool Sand Filter

The sand filter system keeps the pool water clean using filter sand in the tank. Additionally, the pump included in the set circulates the water, ensuring the pool cleaner chemicals in the water are evenly distributed, which also helps maintain water cleanliness. By connecting a pool vacuum to the suction line, debris that has settled on the pool floor can also be removed.
The SPF 180 E pool filter features a 4-position multiport valve with the following functions:
– Filtration: filters and circulates the water, as well as vacuuming the pool
– Backwash: cleans the filter sand in the tank using pool water
– Rinse: the final step in the cleaning process, settling the stirred-up sand and removing dirt from the valve and pipes
– Winterize: used during winter storage, keeps most openings open to allow the sand to dry and ventilate before winter frosts
The device requires 10 kg of filter sand with a grain size of 0.7-1.2 mm or T.I.P. filter balls.
Recommended for all types of pools up to a maximum of 20 m³.
Performance: 250W / 180W
Sand filter flow rate: 4,500 l/h
Pump flow rate max.: 7,900 l/h
Max. head / pressure: 6m / 0.6 bar

ERASPA Fairland 3.5KW SHP03 Mini Heat Pump


Recommended for soft-walled and metal-framed pools with a water volume of less than 20m³.
Key features:
– Ideal heating capacity of 3.5KW (3500W)
– Ideal COP value of 5.5
– Equipped with a 10mA FI relay
– Filled with ozone-friendly R32 gas
– Titanium heat exchanger
– Heating-only function
Operating voltage: AC 230V / 50Hz
Maximum current consumption: 3.75A
Power cable: 3x 1.5mm²
Recommended flow rate: 1-2 m³/h
Noise level at 10m: 36dB (A)
Noise level at 1m: 56dB (A)
Operating temperature range: (air) 10C° – 43C°
At 26C° air, 26C° water, and 80% humidity:
COP value: 5.5
Power consumption: 636W (0.64KW)
Heat output: 3500W (3.5KW)
At 15C° air, 26C° water, and 70% humidity:
COP value: 4.1
Power consumption: 537W (0.54KW)
Heat output: 2200W (2.2KW)

UNIPRODO Pool Ladder 4 Steps

Important considerations for the choice:
– Can be removed for winter storage
– Sturdy and robust
– Made of stainless steel (acid-resistant)
– Space-saving design
It’s true that the elongated handrail version is much more elegant and perhaps provides more comfortable support when climbing out, but we didn’t want to make the small pool and the area around it more cramped.

The choice fell on a 3.5-meter diameter pool because that’s what fit. 🙂
Regarding depth, it could have been 0.9 to 1.5 meters, but the intermediate 1.2-meter depth was appealing because it allows for swimming while requiring less water, meaning less water to heat. Additionally, the sun can more easily warm up the 1.2-meter water column compared to the 1.5-meter one.

Excavating 12 m³ of soil, which loosened to 18 m³ after removal.

The issue of concreting was a major dilemma. In many German, Czech, and Polish videos, they do not concrete. However, from experience, I know that if wet soil freezes, its volume increases. It is true that the water exerts pressure, but it is advisable to lower the water level to the bottom of the lowest water equipment element in winter to keep the pipes water-free and avoid possible frost damage. In this pool, the bottom of the counter-current device is 55cm from the top edge of the pool, which means that the height that becomes water-free is exactly where the upper layer of soil is most likely to freeze and expand. Since there is no counter-pressure from the pool water in winter, the frost can push the pool wall inward.

10cm layer of gravel


As a result of this thought process, I decided to concrete. If I concrete the sidewalls, it makes sense to also concrete the base to prevent uneven settling.

Concrete base guide

I do not expect damage caused by groundwater, because the garage’s 1.7-meter-deep inspection pit has been dry for over 50 years, and one can imagine that during the time of communal construction, no waterproofing was used. That is, only mortar and small bricks were used and it remains dry – it’s in good condition. Groundwater could only be dangerous if the concrete is not waterproof, and mine isn’t, then high groundwater, if it rises above the water in the pool, would seep between the pool liner and the pool wall.

The Insulation Issue

Both the base and the wall received 5cm of XPS insulation, with the base layer structure as follows:

  • 10cm of gravel,
  • 8cm of reinforced concrete,
  • 5cm of XPS,
  • 3.5mm thick vinyl flooring,
  • 1cm of polifoam,
  • and then the pool liner.

5cm XPS insulation on the concrete base

Some argue that insulation at the bottom is unnecessary because heat rises, and the XPS will sink.
My counterargument: It’s true that heat rises, and if the circulation, i.e., the sand filter, wasn’t running (but it is), the water would stratify, becoming hot on top and cold at the bottom. However, circulation mixes the water. If the water is 30 degrees and they say the ground temperature at 1 meter deep is always 15 degrees, then I continuously have about a 20 m² surface area where the 30-degree water cools against the 15-degree ground. That’s why I put XPS at the bottom as well.
Another point is that the XPS will sink unevenly. Numerous videos online show the construction of insulated sunken pools without concrete. They place a 2mm thick vinyl sheet on the XPS. I couldn’t find such vinyl sheets available locally, so I bought 3.5mm thick click vinyl flooring. If 2mm is enough, merely placed next to each other and taped, then 3.5mm thick and click-together flooring should be even better.

Yes, I am the fool who installs flooring under the pool liner. 🙂

The pool’s steel wall set up

The 1cm thick foam was laid instead of the usual heavy geotextile layer simply because I already had it at home, so I didn’t need to buy it. At the junction of the pool base and the wall, a guiding track is typically used to cover and soften the sharp corner. A cheap solution is to smooth sand around it nicely. A more expensive solution involves gluing special trapezoidal cross-section foam material around it. I used leftover expansion strips intended for concrete base use.

1cm thick polifoam instead of the usual heavy geotextile layer

The pool liner installed. We will smooth out the wrinkles with the help of water pressure.

To Concrete or Not?

When considering the construction of the pool sides, I pondered that if I was satisfied with an 8cm concrete base, the sides wouldn’t need more either. So, I cut the 15cm wide formwork block in half, and placed the resulting 7.5cm thick concrete elements with the cut sides facing the insulation. I cut all the sidewall XPS lengthwise to make the curve smoother. When concreting the sidewall, caution is needed because the water level in the pool must always be higher than where the concreting is to avoid pressing the steel wall inward. The XPS helps mitigate this, but the half formwork block only served as formwork outwards. The space between the formwork block and the pit wall was filled with gravel.

Pool wall with halved XPS insulation panels around it.

Concreting with halved formwork blocks

Only the upper half meter of the pool wall was reinforced.


Concreting the upper part

Almost finished around with Semmelrock paving stones

The vertical part is not glued; it only functioned as formwork during concreting. I expect that some elements may fall off or detach in the future, and I will reattach them with adhesive foam. I do not intend to grout the vertical elements because I believe they look more distinctive this way.

For the horizontal surface, I used frost-resistant, flexible adhesive. The joints are also sloped outward. After the adhesive set, I filled these joints with grey silicone, just like the gap between the stone and the pool’s blue plastic edge. Before the silicone fully hardened, I sprinkled and pressed sand onto it, then swept off the excess after it set. This gives a more natural appearance, not looking like grey rubber.


These paving stones are not new; they are repurposed from the previous paving around the pool. I calculated how many pieces of each form I would need for the coping and wall around the pool and used the leftovers elsewhere.


The pool looks finished

Pool Equipment

This is what isn’t visible but makes the pool usable.
The pumps, including the sand filter and the counter-current system, are usually installed in a pit next to the pool. Since the garden is very small, all this was placed in the garage (which is quite large).

Pool equipment

The heat pump is typically used outdoors because it cools the air, thus cooling the garage. While this is good, the higher the air temperature, the better the heat pump’s efficiency. What do we want, a cooled garage, or cheap hot water? For cheap hot water, the garage door is left open. Even then, it’s noticeable that it’s cooler, but this solution works well. The main goal was to avoid cluttering the small garden with equipment and noise.

This has worked perfectly. Neither the sand filter nor the heat pump’s noise can be heard in the pool (even with the garage door open), allowing complete relaxation unless we turn on the radio.


Since the pumps are in a pit, they are positioned deeper, ensuring they can properly pick up and circulate the water.At ground level, the initial start-up encountered difficulties since the sand filter is less powerful and located at ground level, making it hard to initiate circulation. To assist, I used a hose which I pressed into the skimmer, allowing me to expel some of the air. This method also benefited the counter-current system by inserting the hose into the outlet before the first activation.


The 3-horsepower electric motor of the counter-current system is also inaudible. While the flowing water does produce noise, especially when mixed with air, the sound of the electric motor itself is not heard.

Swimming with the counter-current system (swim machine) – on a low setting

The counter-current swim machine is nominally capable of circulating 70,000 liters of water per hour. I was somewhat concerned about this specification, as some sources suggest a pool at least 6 meters long is necessary.

However, the flow rate can be adjusted by rotating the outlet nozzle and mixing in air, which ultimately posed no issues. The maximum flow rate is suitable for real athletes and fast swimming, but the reduced setting is more than sufficient for recreational breaststroke.

The swim machine’s panel features a single pneumatic button. This button controls the pneumatic switch in the electrical distribution box via pressure changes in a long air tube. There are no other on/off controls, and none are necessary, aside from the main switch in the electrical box and the separate 3-phase safety relay.

This is worth mentioning because all other electrical devices are controlled in a different manner, as detailed below.

Pool electrical wiring

Smart System – Is it Necessary?


Smart system, smart home, smart speaker? When does something become “smart”? Some manufacturers label any device with a remote control or wireless signal transmission as “SMART” for marketing purposes.


The essence of the matter is that if I want to control three devices from three different locations, and one of these locations is in another building, a significant amount of wiring is required, not only to be installed but also to be neatly concealed afterward.


It’s much simpler to solve this wirelessly with radio frequency. If it’s already radio frequency, then it’s just a step away from the “smart” approach, meaning why not connect it to the house’s WiFi? Once it’s on WiFi, it can be accessed and controlled through a mobile application. If there are smart speakers (because why wouldn’t we have thousands of radio stations in a palm-sized speaker, activated by simply telling it what we want to listen to), this “smart” system is intelligent enough to detect new smart devices on the WiFi and inform you that they can be used or controlled through it.

What if we forget a switch in the on position? Well, if it’s smart, we can turn it off (or on) with our mobile phone even if we are not at home, as long as we have mobile internet. It’s more convenient to switch it via mobile than to go back and check if we turned it off.

The bottom line…

As a convenience feature, I installed three V-TAC VT-5130 SMART relays that can be used via WiFi and radio frequency. These can be controlled with two VT-5133 three-circuit SMART radio frequency (wall remote) switches, a mobile phone application, and verbally through an Amazon Alexa smart speaker.

Specifically, all three relays will control outlets since the connected sand filter lacks a switch, and the pool heating unit (a heat pump) doesn’t have an explicit on-off switch—only a button to activate the heating demand. Even when turned off, the entire heat pump remains powered and displays the temperature. Although there is a portable safety switch near the plug, it’s not primarily intended for this purpose.

Therefore, the three relays are associated with pool operations.

  • The first relay will control the sand filter.
  • The second relay will control the pool heater (i.e., the heat pump).
  • The third relay will control an analog radio.

Yes, it’s somewhat unusual to toggle an analog radio via WiFi or Alexa, given that a smart speaker could suffice, but in this setting, it seemed the most logical solution.

For more information on the WiFi relay, visit: https://ledrex.hu/vt-5130-smart-wifi-rf/
For more information on the 3-circuit RF switch, visit: https://ledrex.hu/vt-5133-smart-rf/
For information on the entire product family, visit: https://ledrex.hu/v-tac-smart-vezeteknelkuli-rf-wifi-kapcsolocsalad/

If you’re interested in a video about the pool’s smart system, watch the following video!


Photos of the completed pool


Experience the pool construction in the video below:


Pool Solar Cover

Based on my experience, it can increase the pool water temperature by 1-4 degrees Celsius.
When circulation is off, the water layers, and in 30-degree heat, the top layer under the solar cover reached 37 degrees. When I turned on the circulation, it mixed the water, cooling it down to 32 degrees – all without additional heating.


"Do it yourself!
Don't worry if you don't know how—neither did I.
The project took three months of leisure activity."
Tamás Tóth