The NUFilter

A breakthrough in pool water treatment

Nufiltration decided to apply the particular advantages of the NUF™ technology in the field of swimming pool water treatment and to develop a dedicated unit for the application.

The technology has been approved and recognized as a proper solution in swimming pools by the Israeli Ministry of Health.

We consider the NUF™ technology capable to replace the various conventional water treatment processes currently used in the market and therefore to be a revolutionary solution in the pool water treatment field

Swimming pool water treatment technologies


The basic water treatment processes for swimming pools have fundamentally remained unchanged for decades and are based on:

  • Removal of suspended particles by mechanical means (sand filtration, cartridge filtration, etc.)
  • Killing bacteria and microbiological pollutants with massive doses of chemicals
    Used in public pools but mainly in private pools, where maintenance and equipment automation are minimal, this method requires injecting consistent quantities of chlorine (or other oxidizing agents) in order to protect swimmers from microbiological contamination or illness. This practice is routine and widely used.

However, it is a well-known fact that the presence of chlorine in pool water negatively affects the swimmer's experience and may cause itching, a burning sensation of eyes, nausea, bad smells and more.
Moreover, scientific research clearly demonstrates that even the use of medium concentrations of chlorine in swimming pools (0.8-2 ppm), may cause harmful and even cancerogenic threats, created by the combination of chlorine with organic substances naturally secreted by bathers (disinfection by-products – DBP - like THMs).

Current approaches for the improvement of pool water treatment

In recent years, huge efforts have been invested in facing the threats and dangers caused by conventional treatment methods, attempting to reduce or even eliminate DBPs.
Among the most common is a multi-stage combined process: coagulation, powdered carbon absorption and slow sand filtration.
This process reduces free chlorine levels in water to a range of 0.3 – 0.6 ppm (as required by German DIN 19643 standards),this providing an active disinfecting agent at a minimal and almost non-detectable range for humans.
Another innovative swimming pool water treatment process, which is rapidly gaining recognition and approval in the industry for its tangible benefits, is Ultrafiltration (UF).
The implementation of semi-permeable membranes with a nominal filtration rate of up to 0.04 µ in the pool recirculation loop provides immediate results: removal of suspended solids together with a drastic reduction of microorganism and biological pollutants in one single pass.

The UF treatment process has recently been approved and included in German DIN standards (see DIN 19643-4 part: "Treatment of water of swimming pools and baths – Part 4: Combinations of process with ultrafiltration").
According to the DIN 19643-4 standard,implementation of UF technology in swimming pool treatment brings several significant benefits versus all other treatment processes:

  • Reduction by 50% of the circulation loop capacity
  • Reduction by 50% of chlorine dosing
  • Higher "load capacity factor" ("k" – no. of swimmers per each m3)

In conclusion, Ultrafiltration can be considered one of the BTs (Best Technologies) for this application.

However, despite the fact that the two treatments described above provide significant benefits versus the "conventional processes", their broad implementation in the market is being slowed-down by two main obstacles:

  • Complete multi-stage and/or UF systems are extremely heavy, complicated and space consuming;
  • Installation costs are prohibitive. Therefore, these technologies are viable only to a restricted range of users and customers, namely public pools with considerable economical means and space. The main segment of the market held by private pool owners simply cannot afford such solutions. Owners of private pools and of public pools with restricted economical means are therefore condemned to suffer exposure to chlorine or other disinfection agents (and harmful DBPs) in massive doses.

The NUFilter breakthrough

The vision for NUF technology implementation in pool water treatment is to provide the public of swimming pool users with a compact and reliable system that produces premium quality UF water, free of suspended solids, bacteria and organic matters (at an even higher level than the water produced by commercial UFs) – but still affordable.
In other words, to break through the afore mentioned obstacles and to transform the BT (Best Technology) in BAT (Best Affordable Technology). In a nutshell, the swimmer experience in a pool treated with a NUFilter is similar to bathing into a natural water body.

What is so special in this picture ??

  • (see the answer at the end of the document)

The NUF™ membrane technology

The NUF purification process takes place ‘on-line’, feeding raw water at low pressure (from 0.5 bar) through an NUF type membrane.
NUFs are, therefore, elements of the highest level of Ultrafiltration with an absolute filtration rate of 0.03 μ. Produced as medical devices, they create a real and almost absolute filter barrier to a diverse range of pollutants existing in various sources, including swimming pools, namely suspended solids, bacteria, microorganisms of different kinds, organic matter, macromolecules and more.

Moreover, thanks to the specific characteristics of the fibers which are manufactured with an extremely smooth membrane surface, all the pollutants and fouling agents rejected by the
NUF membrane during operation, cannot stick to the surface and are easily removed by means of a simple backwash.
The performance of NUF membranes is almost unbeatable for water treatment, especially within the range of Ultrafiltration membranes produced by the main suppliers in the field.

The complete process and technology received formal approval by the Israeli Ministry of Health, for use in water treatment technology in swimming pools.

NUFilter products

NUFiltration Ltd. has developed a range of products for the implementation of NUF™ membrane technology, protected by a worldwide applied patent, in pool treatment:

  • The NUFilter – an affordable and compact unit designed mainly for private pools with a volume of up to 80 m3. The NUFilter is available in two modes: manual activation of backwash mode or automatic activation of backwash mode;

Rendering of the NUFilter-10M unit

Industrial NUFilter plants – modular, fully automated units for public pools.

NUF units for public swimming pools of 150 and 600 m3 volume

The NUFilter

The NUFilter is a simple, compact, easy-to-install and affordable unit, which integrates all the advantages of the NUF technology and allows private pool owners and their guests to enjoy the many benefits of the BT (Best Technology) available on the market:
swim in crystal clear water with an extremely low chlorine impact.

The compact NUFilter is installed as the only pool treatment device and is connected to the circulation pump inlet, to the pool and to the drain.

As previously stated, thanks to the smooth membrane surface, a short backwash is sufficient to remove clogging and fouling agents from the membranes. Therefore, backwash is operated with the same circulation pump using pool water.

The NUFilter operates in two modes:

  • Filtration mode
  • Backwash mode

NUFilter is built in a compact box for easy installation in the machine room of a private pool, and is available in two versions:

NUFilter-10A - This version provides for the automatic activation of backwash and is equipped with automatic valves and PLC for full and controlled automatic operation of the unit (optionally activated by Smartphone through Bluetooth connection)

NUFilter is built in a compact box for easy installation in the machine room of a private pool, and is available in two versions:

NUFilter-10M - This version provides for manual activation of backwash and is equipped with two 3-way hand valves for filtration/backwash activation

The only regular requirement for the maintenance of the NUFilter – in the manual mode only - is the manual activation of a backwash at a frequency which depends on the load capacity and the pool environment (open air, indoor etc.).
The standard backwash frequency in an average private pool during the season varies from once a week to twice a week.
The NUF membrane elements are fully guaranteed for a period of three years, while the lifetime expectancy is of 5-6 years. Eventual NUF elements replacement is a simple, quick and non-expensive operation.

Other characteristics of the NUFilter:

  • Dimensions (in both versions): 90 x 79 x 82 (L x W x H in cm)
  • Weight: 55 kg. (NUFilter-10M); 67 Kg. (NUFilter-10A)
  • Power supply: 110 VAC or 220 VAC (NUFilter-10A only)
  • Inlet water requirements: hair filter (usually supplied integrally with the circulation pump)

The NUFilter has been tested under tough environmental conditions and with high load factors in a therapeutic pool, populated by tens of patients per day.
A sampling program was applied on the test, while all the tests were carried out by an official Lab authorized by the local Ministry of Health.
The NUFilter performances, combined with an extremely low concentration of chlorine (< 0.4 ppm) has been tested consecutively for more than one year with the following results:

  • Coliforms: < 1 col/100 ml
  • E-coli (fecal): < 1 col/100 ml
  • Psaeudomonas Aerouginosa: < 1 col/100 ml
  • Concentration of combined chlorine: 0.1-0.2 ppm as Cl2
  • Turbidity (at NUFilter outlet): < 0.1 NTU
  • Viruses removal rate: 5-7 log (tested in waste water)

Benefits in private pools

  • The NUFilter is unique in the market of private pools. No private pools are equipped with a system based on the UF technology due to their high costs and complicate application.

  • Most public pools cannot afford the installation of UF systems as well. Only few public pools (mainly in Germany) are benefiting nowadays of the big advantages presented by the UF technology. NUF systems can provide an affordable solution also to this market segment.

  • Simplicity of the installation and operation. While systems based on commercial UF membranes require a separate loop (thus a separate additional pump, piping, valves etc.) for the activation of backwashes and cleaning procedures, the NUFilter takes advantage of the unique smooth membrane surface of the NUF element -
    operating the backwash with the pool water itself. The hydraulically driven countercurrent flow is more than sufficient to provide for the regular cleaning of the membranes.

  • Consequently, the NUFilter is installed and operated similarly to a sand filter (and even in a simpler way) – inlet connection to the pump, outlet connection back to the pool and connection to the drain for the backwash procedures.

  • The only regular required maintenance action is the backwash: in the manual version is activated for a period of 60 seconds in a frequency of once/twice a week by simply turning two valves, while in the automatic version and in the systems for public pools the operation is fully in an automatic mode

  • The NUFilter replaces the current, commonly used sand filters while reducing drastically the use of chlorine, bromine or other oxidizing agent – at a cost similar to the one of the conventional treatment.

  • Small installation cubicles. Most of the machine rooms housing pool water treatment equipment are small and uncomfortable. The unit should therefore be compact and still accessible to the user and/or the "pool-man" for maintenance and operation

  • Thanks to the membrane characteristics, quantities of water used for backwash are lower than the one used for sand filtration.

  • The swimmer experience in a pool treated with a NUFilter is similar to bathing into a natural water body.

Additional Benefits in public pools

The same above mentioned benefits are achieved in public pools as well,
while additional advantages are :

  • Tremendous energy savings (due to the reduction by 50% of the circulation capacity, as approved by the DIN 19643)
  • Water savings
  • Chemical dosing reduction
  • Higher load factor. The DIN standard allows for a "k" load factor of 1 N/m3 with UF treatment, versus 0.5 N/m3 with "conventional" treatment

  • The only animals on earth which accept to swim in a water body full of chemicals and high amounts of chlorine are..human beings ! A duck will only swim in water with an imperceptible amount of chemicals..and he will be ready to get wet ONLY in a swimming pool treated with a NUFilter