LED lighting for swimming pools

Analysis of operational, structural and material issues related to LED lighting systems in swimming pool environments.

Designing pool lighting is one of the most challenging tasks in lighting engineering. While modern LED technology offers better appearance and lower energy consumption than older lamps, it introduces entirely new technical challenges.

The interior of a pool is an extremely harsh environment – high humidity and the presence of chlorine and salt create a mixture that destroys electronics. The main threats to LED fixtures include not only the risk of flooding, but also:

Chemical attack: Chlorine vapors can corrode delicate components inside the fixture.
Material degradation: Specific conditions accelerate the wear of semiconductors and optical systems.
Thermal problems: Difficulty dissipating heat in tightly sealed enclosures.

As a result, durable pool lighting requires the use of advanced materials and specialized design solutions that protect the electronics from the damaging effects of the environment.

Oświetlenie LED na basenach i pływalniach

Characteristics of the pool environment as an aggressive corrosive agent.

Understanding the problems of LED lighting first requires a precise analysis of the external factors prevalent in swimming pools and pool decks. Typically, there is very high humidity (often above 60%) and high temperatures (28°C - 30°C), which causes water with chlorine to constantly evaporate, creating an aggressive atmosphere. Here are the main factors that damage standard lamps:

Chlorine and salt mist.

Chlorine is present in the air as a gas. Combined with moisture, it settles on lamps, damaging materials that are not resistant to it. It is even more difficult in saltwater pools, where so-called salt mist is created. It is extremely corrosive and can penetrate the smallest gaps in the housing.

Destruction mechanisms. (Summary Table)

Degradation Factor	Impact Mechanism	Effect on LED Luminaire
Chlorine (Gas/Liquid)	Polymer oxidation, metal corrosion, silicone penetration	Diode darkening, loss of seal, contact corrosion
Salt Mist (NaCl)	Accelerated pitting corrosion, surface stains	Structural degradation of the housing, short circuits
High Humidity	Condensation, hydrolysis of protective coatings	Corrosion of electronics, fogging of optics
Ambient Temperature	Acceleration of chemical reactions, LED thermal degradation	Shortened lifespan of L80B10, changes in LED color

Which solutions should I choose?

The use of LED lighting in such conditions requires abandoning standard commercial solutions in favor of fixtures with a high corrosion resistance class, defined according to the ISO 9223 standard. For swimming pool halls, it is recommended to use fixtures with a C5 corrosion resistance class that have passed salt mist tests lasting at least 1000 hours.

Lighting fixture design and material resistance

The right design of the luminaire is the foundation for its long-term operation. Materials used in swimming pools must be resistant not only to water itself, but also to the specific mixture of chlorides and acids produced as a result of water treatment.

Pool chemicals and internal degradation of LEDs

The most critical and least visible problem for users is the impact of swimming pool chemicals on the structure of the LEDs themselves. Studies have shown that chlorine and other volatile chemicals can penetrate the interior of the luminaire even with a high IP rating.

Mechanism of Volatile Organic Compounds (VOCs) penetration

Although LEDs appear to be tightly sealed, their weakest point in harsh conditions is, paradoxically, the material that's supposed to protect them—silicone.

Most powerful LEDs have silicone lenses. This material is heat-resistant and transparent, but it has one hidden drawback: it's "leaky" at the molecular level. It acts like a sponge that allows gases to pass through.

How does a diode get damaged?

The entire light destruction process takes place inside the lamp in three steps:

Evaporation: As the lamp lights and heats up, invisible chemical vapors (including chlorine from the pool environment) are released from the adhesives, seals, and electronic boards inside the housing.
Penetration: These gases easily pass through the porous structure of the silicone and reach the very heart of the diode (the chip).
Browning Phenomenon: Under the influence of high temperature and strong blue light, these chemicals "burn" onto the chip. A brown or black deposit forms, blocking the light.

Effects on lighting

Brightness loss: The dark deposit acts as a filter, causing the lamp to glow dimmer.
Color change: The light may become unnaturally yellow or brown.
Overheating: The deposit traps heat near the chip, which can lead to complete burnout of the diode.

To prevent this, professional pool lights use special "VOC-free" components (free from harmful vapors) and reinforced diodes that are resistant to gas ingress.

Swimming pool design and lighting system integration

Designing pool lighting is more than just a matter of aesthetics. It's primarily about safety. The key issue here is physics: the water surface acts like a mirror, which can completely blind lifeguards.

Combating mirror reflection.

When light reflects off the water surface instead of penetrating it, blinding reflections are created. This prevents lifeguards from seeing what's happening at the bottom of the pool. To prevent this, three proven methods are used:

Perimeter lighting: Lamps are mounted along the edges of the pool, not directly above the water. This allows the light to shine at an angle that minimizes reflections into the eyes of staff.
Indirect lighting: This is one of the most effective methods. The light is directed at a bright ceiling, from which it reflects and returns to the bottom as a soft, diffused light. This completely eliminates glaring light spots on the water surface.
Appropriate angles: The best underwater visibility is achieved when the light falls at an angle no greater than 55° to the vertical. This allows the rays to "pierce" through the surface instead of being reflected off it.

Safety in practice.

Good lighting must meet the needs of three groups:

Lifeguards: They must see the bottom without reflections.
Swimmers: The light must not blind them when swimming breaststroke or on their backs.
Spectators: The lighting should ensure comfortable viewing of the competition.

Proper planning of these systems is key to avoiding dead zones in the water where a person could become invisible to the lifeguard.

Photobiological protection and risk groups (RG)

Due to the high intensity of light emitted by small LED chip surfaces, it is important to test photobiological safety in accordance with EN 62471. Pool luminaires, especially those installed within the sight range of children and the elderly, should meet the requirements of group RG0 (no risk) or RG1 (low risk). Group RG2 is only acceptable in high installations where it is not possible to stare directly at the light source from a close distance for a long period of time.

Summary

The use of luminaires with a high corrosion class (C5) and components resistant to the penetration of volatile chemicals and chlorine is key to the durability of the system. In addition, the lighting design must prioritise safety by eliminating glare on the water surface (e.g. through indirect lighting) and ensuring adequate photobiological protection to provide lifeguards with good visibility of the bottom and comfort for users. The right combination of advanced material technology and thoughtful design is the only guarantee of long-term and safe operation.

FAQ:

🔹 Why does LED lighting in swimming pools deteriorate quickly?

➡️ LED lighting in swimming pools is damaged by high humidity, chlorine and salt mist, which cause metal corrosion, gas penetration into silicone lenses and semiconductor degradation. These factors accelerate diode darkening, loss of tightness and decrease in brightness.

🔹 What does corrosion class C5 mean and why is it important?

➡️ Class C5 according to ISO 9223 means the highest corrosion resistance for highly aggressive environments, such as swimming pools or coastal facilities. C5 luminaires undergo salt spray testing for a minimum of 1,000 hours, which guarantees their durability.

🔹 How does chlorine damage LED luminaires?

➡️ Chlorine in gaseous form reacts with metals and polymers, causing oxidation and corrosion. It can also penetrate silicone, reaching the interior of the LED, where it causes so-called browning – darkening and deterioration of light output.

🔹 Why are silicone LED lenses susceptible to gas permeation?

➡️ Despite its thermal resistance, silicone has a microporous structure that allows volatile organic compounds and chlorine to pass through. These gases reach the LED chip and lead to permanent optical degradation.

🔹 How to design pool lighting to avoid dazzling reflections?

➡️ Three solutions are used:

perimeter lighting mounted at an angle,
indirect lighting reflected from the ceiling,
selecting an angle of incidence of ≤ 55°, which allows light to penetrate the water and improves the visibility of the bottom.

🔹 What do the risk groups RG0–RG2 mean in the context of LED?

➡️ These are the photobiological safety classes defined in EN 62471:

RG0 – no risk,
RG1 – low risk,
RG2 – moderate risk (permissible in high-rise installations).
Pool luminaires should be RG0 or RG1.

🔹 Which LED fixtures work best in a swimming pool environment?

➡️ It is best to use luminaires:

Corrosion class C5,
VOC-free LEDs,
High IP rating,
Chlorine and salt mist resistant construction,
Tested in salt mist for at least 1000 hours.

If you want to consciously use the potential of light in your investment, it's worth starting with a well-designed lighting system.

LED lighting for swimming pools

Analysis of operational, structural and material issues related to LED lighting systems in swimming pool environments.

Characteristics of the pool environment as an aggressive corrosive agent.

Lighting fixture design and material resistance

Pool chemicals and internal degradation of LEDs

Mechanism of Volatile Organic Compounds (VOCs) penetration

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Swimming pool design and lighting system integration

Photobiological protection and risk groups (RG)

Summary

FAQ:

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