An Introduction to Hot Tub Filters

The filtration system isn’t the most exciting part of your hot tub or spa, but it is certainly one of the most important! Filters help to keep the water clean, reducing the build-up of potentially harmful bacteria and preventing dirt and debris from getting into the working parts of the system and clogging it up or causing damage.

Why are hot tub filters important?

Warm water can be an encouraging environment for bacteria, some of which may be potentially harmful to humans. Of course these are primarily managed by the chemicals in your spa water, but a good filter certainly helps.  As well as protecting the users in this way, the filter also protects the workings of the hot tub itself.  During use it’s quite common for dirt or small pieces of debris such as grit, leaves and the like to get into your hot tub water, along with oils and dead cells from the skin.  The filter prevents these from getting into the pipes and workings of the hot tub and causing any damage or obstructions.

How do Filters Work?

There are several different types of hot tub filtration system used in different brands and models of spa:

  • Cartridge filters are the most common. The cartridges are usually plastic and house a variety of filtration media which capture bacteria and fine dirt.  They are effective, affordable and easy to maintain.
  • Diatomaceous earth filters are essentially a type of cartridge filter containing a fine powder called diatomaceous earth, which is the fossilized remains of diatoms, a type of hard shelled algae. It is very effective at capturing bacteria.
  • Ceramic filters use a porous clay pot type structure to filter the water, often supplemented by another filtration medium such as activated carbon.
  • Sand filters are used in some types of hot tub. They are effective but need to be cleaned very regularly.

How do I look after my filters?

In order to be effective, your filters need to be kept clean.  By their very nature, over time they will collect a build-up of dirt and become clogged. Different types of filter need different levels of maintenance.  The most common types of cartridge filter can be cleaned simply by removing them from the hot tub and rinsing them every few weeks, with an occasional deep clean by soaking in specially formulated cleaning products.  When you remove the filter to clean it, it’s a good idea to examine it carefully, and if it appears damaged in any way, it should be replaced.  For more information read our article on cleaning hot tub filters.