What’s the difference between a 400 and 500 micron pool cover?

When choosing a pool cover, understanding the difference in the various thicknesses available can help you make the right decision for your pool. But what exactly is a micron, and does a thicker cover mean better performance? In this blog, we’ll explain microns, explore how thickness impacts performance, and clarify why the colour and material of your cover are often more important considerations.

What is a Micron?

The thickness of pool covers is often measured in microns. A micron, short for micrometre, equals 1/1000th of a millimetre or just over 25 thousandths of an inch—extremely small! To put this into perspective, a human hair can be as thick as 180 microns, meaning the difference between a 400 and 500 micron pool cover is often finer than a strand of hair.

When referring to microns in pool covers, it describes the total film thickness, excluding the air cells within the bubbles. You may also come across the term ‘grade,’ which is used interchangeably with micron.

Not all pool covers are created equal

It isn’t just thickness which impacts a cover’s longevity, but also the quality of the materials within. All of our GeoBubble™ pool covers are manufactured from high grade materials and contain a unique blend of pigments and a specially formulated UV stabilisation package to maximise both performance and lifespan. The high performance Guard covers, such as EnergyGuard™ Selective Transmission also contain a higher level of UV protection which further boosts longevity, allowing for a warrantied lifespan of 8 years.

Read about our on-site testing here

Longevity

Both 400 and 500 micron standard GeoBubble™ covers last up to 25% longer than alternative covers incorporating the traditional round bubble design. The extensive warrantied lifespan of GeoBubble™ pool covers is thanks to the patented GeoBubble™ design which ensures that our pool covers are 50% thicker at their thinnest point than traditional round bubble covers. In addition to this, GeoBubble™ covers are manufactured from only the highest quality blend of performance polymers and specially formulated pigments and UV stabilisers.

For standard GeoBubble™ covers, the thickness of the cover primarily determines the cover’s expected lifespan. 400 micron pool covers are warrantied for 4 years, whereas a 500 micron pool cover has an extended warrantied lifespan of 5 years. This is because the added thickness means that it takes longer for the material to degrade over the course of its lifespan.

Solar Heating Performance

When it comes to solar heating and heat retention, there is minimal difference between a standard 400 and 500 micron GeoBubble™ pool cover of the same colour. This is because the transfer of solar energy and the insulative properties of the GeoBubble™ air cells remain consistent regardless of cover thickness. The most significant factor influencing solar heating efficiency is the colour of the pool cover. More transparent covers allow greater solar energy penetration, resulting in increased heating capacity. For a deeper dive into how colour affects performance, take a look at our blog: Which Colour Pool Cover Should I Buy?.

Opaque Black

Not Transparent

Up to 0°C

Warmer

Blue/Silver

Very low transparency

Up to 0°C

Warmer

Light Blue

Most Transparent

Up to 0°C

Warmer

Sol+Guard™

Most Transparent

Up to 0°C

Warmer

An exception to this rule is the EnergyGuard™ Selective Transmission pool cover, which despite its midnight blue appearance, is considerably more transparent to solar heating energy than standard GeoBubble™ covers. This allows for a warmer pool by up to 7°C and a 70% reduction in heating costs. EnergyGuard™ Selective Transmission also blocks the visible light from entering the pool, inhibiting algae growth and reducing chemical consumption and maintenance time.

For those looking for the best durability and efficiency, our high-performance GeoBubble™ Guard range is the clear choice. These products have a warrantied lifespan of 8 years—double that of our standard 400 micron covers. Beyond their impressive lifespan, GeoBubble™ Guard covers deliver exceptional energy and resource savings, offering a return on investment of up to 10 times. Choosing an EnergyGuard™ Selective Transmission cover further amplifies these benefits, saving up to twice as much energy and money over its lifetime compared to a standard GeoBubble™ cover. Discover more about these significant savings in our EnergyGuard™ Selective Transmission heat pump study.

What is Reinforcing Weave?

All our high performance GeoBubble™ Guard materials are available with a reinforcing weave top layer. These reinforced covers – sometimes referred to as 800 micron – are up to 2.5x as strong as the Guards covers alone and are designed for larger pool covers which are likely to have a harder life when they are rolled on and the pool. With enhanced UV stabilisation the the reinforced weave Guard covers are suitable for the harshest environments.