Why a good filtration system matters in a hot tub

Posted by Laura Onder de Linden

8 September 2026

On 2 December 2023

One of the great things about owning a cedar hot tub is knowing it’s always ready for a relaxing soak. Crystal-clear water is an important part of that experience, with a well-designed filtration system working continuously in the background you’ll enjoy a fresh and inviting tub year-round.

Why filtration is important

Every time you use your hot tub, small particles enter the water. This can include dirt, leaves, pollen, body oils, and other debris. Without proper filtration, these particles remain in the water and quickly affect the clarity and quality of the water. A filtration system continuously circulates the water and removes these unwanted particles. The result is cleaner water, less maintenance, fewer water treatment products, and a more enjoyable soaking experience.

The difference between wood-fired hot tubs and spa systems

Many traditional wood-fired hot tubs operate without an integrated filtration system, which means the water needs to be changed much more frequently.

Some owners choose to add an external filtration system, but this creates additional maintenance and can be less practical during winter. In colder climates, external systems may require extra protection against freezing temperatures.

A cedar hot tub equipped with a modern spa system takes a different approach. Filtration is built into the system and can run automatically according to pre-programmed cycles. This means the water is continuously cleaned with very little effort from the owner.

To make water care as simple as possible, Northern Lights Hot Tubs are equipped with industry-leading filtration systems. We also offer hybrid systems that combine a wood-fired heater with a spa system, allowing you to enjoy the character of wood-fired heating while benefiting from built-in filtration, automatic water circulation, and the convenience of a modern spa system.

Not all filters are the same

A common misconception is that all hot tub filters perform equally well. In reality, the quality of the filter itself makes a significant difference. Most modern spa systems and premium hot tubs use a cartridge filter. Inside the filter, you’ll find a series of folds, called pleats. These pleats create the filtration surface area.

The more pleats a filter has, the larger the filtration surface becomes. A larger surface area allows the filter to capture more particles while maintaining good water flow through the system.

Simply put, more pleats generally mean more effective filtration and cleaner water.

Cartridge filters vs sand filters

You may have heard of sand filters, which are commonly used for swimming pools. While they work well in that environment, hot tubs operate under very different conditions. Because of the higher water temperatures and smaller water volumes found in hot tubs, cartridge filters are the preferred solution. This is why they are widely used in modern spa systems and hot tubs.

The Northern Lights approach to water quality

At Northern Lights Hot Tubs, our spa system combines cartridge filtration with additional water treatment technologies, including ozone purification and mineral ionisation.

The filtration system can be programmed to run automatically, this way you’ll enjoy excellent water quality with minimal effort. As a result, the water can typically remain fresh for months rather than requiring constant draining and refilling. This allows you to spend less time maintaining your hot tub and more time enjoying it.

Clean water makes all the difference

A filter may not be the most visible part of a hot tub, but it is one of the most important. A high-quality filtration system helps keep the water clean, reduces maintenance, and makes ownership significantly easier throughout the year.

Discover our spa system and see how integrated filtration, automated heating, and advanced water treatment work together to make owning your hot tub simple and enjoyable throughout the year.