Light decay of LED underwater lights

Luminous decay of LED underwater lights

LED is currently the most widely used underwater lighting source. Although LED lighting has many advantages, such as safety and energy saving, it is still not immune to light decay. I will take you through the light decay and teach you how to deal with the light decay of LED underwater lights.

What’s the light decay?

Any kind of lighting equipment has a complete luminous structure. Their luminescence principles are different, but they all have luminescent materials.

The luminescent material of the tungsten lamp is the tungsten filament in the bulb, and the luminescent material of the LED is the semiconductor inside the lamp bead. Luminescent materials can suffer irreversible loss or damage during use, resulting in a permanent decrease in luminous brightness. We call this phenomenon light decay.

When the lighting product produces the phenomenon of light decay, its power consumption does not decrease due to the reduction of brightness. Light decay is a common phenomenon in all types of lighting equipment. We cannot eliminate light decay, but we can slow it down.

Nowadays, some high quality LED lights have a typical life span of 50,000 hours. If you use poor quality LED underwater lights or use them incorrectly, the decay of LED lights can become very fast.

High quality LED lumen decay model

High quality LED lumen decay model

Causes of light decay in LED underwater lights


Heat is the main cause of light decay. When converting electrical energy into light energy, lighting devices cannot achieve a 100% conversion rate. They always convert some of the electrical energy into thermal energy, which causes the LED light to heat up.

In the following situations, the speed of light decay will be accelerated:

Inferior LEDs

Some factories use inferior LEDs which not only have a fast light decay rate, but also have a short service life, and are also prone to damage under normal use.

Poor heat dissipation ability of LED chips

When the heat dissipation ability of the LED chip is poor, it may be that the heat dissipation design is defective or the processing technology is faulty, resulting in low thermal conductivity efficiency. When used continuously, the LED chip heats up due to the accumulation of too much heat.

LED light design is unreasonable

LED underwater lights often integrate a large number of LED chips. Each chip is an independent light-emitting heating unit. When arranging multiple heating units too densely or using a metal substrate that is too thin to assist the LED chip in heat dissipation, it is easy to cause the temperature to rise due to heat accumulation.


Acids, alkalis and salts easily corrode LED chips. Corrosion of the light source part may seriously affect the light output, service life and lighting effect of the LED underwater light. Sometimes you have to replace the lamp or light source with a new one for this.

Insufficient protection

The underwater lights with IP68 protection can work in swimming pools, hot springs, ponds, fountains, oceans and other underwater environments. If it is lower than this waterproof level, it is easy to cause burnout, corrosion, short circuit and other problems due to water ingress.

Irregular use

If the operation is not standardized during installation and use, the high-quality LED underwater lights will also accelerate the light decay speed.

Use constant voltage driver

LED lights should be driven by constant current. Although it can still work normally when driven by constant voltage, it will lead to faster light decay.

Drive current is too large

The working conditions of LED lamps are very harsh, and the driving current exceeds the rated current, and it is more likely to cause light decay.

Using non-high temperature resistant LED lights in high temperature pools

Some LED underwater lights are not high-temperature-resistant products. Using normal underwater lights in high-temperature scenes such as bathtubs and hot springs will easily burn them out. Even if they do not burn out, their light decay speed will become faster.

Heat resistant underwater luminaires usually use aluminium or copper with good thermal conductivity as the internal metal substrate for heat dissipation. In addition, the interior of the luminaire body is provided with a thermally conductive film and coated with thermally conductive silicone grease to aid heat transfer.

Ordinary underwater lights do not have such a comprehensive heat dissipation design. When forced to work in a high-temperature underwater environment, the above-mentioned problems of light decay or burnout will occur because of heat accumulation.

How to deal with LED underwater light light decay?

Choose high-quality LED underwater lights

You can judge by the LED chip brand, IP protection level and certification of the underwater light.

WAKING is a professional LED underwater light manufacturer. All our luminaires use high quality LED chips from CREE/OSAM or EPISTAR. These chips have good heat dissipation capabilities and proven and stable processing technology. We will test each batch of products for waterproof, salt spray and aging. Most of our products come with a 2-3 year warranty. If you experience a problem with one of our products within the warranty period, please contact us.

WAKING Lighting

Design, Installation Specifications

If you’re experienced, you can certainly do it yourself. Otherwise, it is best to leave it to a professional. Design and installation specifications can not only slow down the decay process of LED underwater lights but also avoid other problems.

Manufacturers of LED underwater lights have experienced engineering teams. If you purchased your LED underwater light from a manufacturer, ask them for assistance.

Replace with new LED bulbs

LED lights with serious light decay can still work normally after replacing them with a new light bulb. If your underwater light uses PAR56 or E27 standard interface, you can buy a new light bulb with the corresponding base to replace it. The replacement process is very easy, which will save you a lot of money.

Matters needing attention

It is not recommended to use excessively powerful underwater lights to increase brightness to deal with future light decay problems, which will waste a lot of electricity. Excessively bright lights can create visual discomfort, causing glare or other types of light pollution problems.

Are you looking for a professional underwater light supplier? Contact us now!

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