The Importance of Hot Tub Filters

The Importance of Hot Tub Filters

Filters are a hot tub’s most important accessory for keeping water clean, clear and ready to use. They help to reduce strain on your spa’s pump and minimize chemical usage.

Without a filter, your hot tub would quickly fill with contaminants and become unusable. Keeping your filters clean is critical to maximizing your filtration system’s performance and longevity.

Suction Side Filtration

Suction side systems are the simplest and most common way of filtering your hot tub water. They skim the top of the spa water using a pump and filter basket removing body oils, dirt, hair, bugs and other debris. They can also remove heavy minerals like sand that tend to fall to the bottom of the spa and need to be manually removed. Unfortunately, suction side filtration systems aren’t very efficient as they need to run for 12-24 hours per day and waste energy.

Another drawback to suction side filtration is that they aren’t very effective at reducing dissolved minerals and chemicals like chlorine. These contaminants can then build up in the plumbing and other equipment of your spa. A dirty or clogged filter will also reduce circulation and increase your energy costs.

Typical cartridge filters are made of pleated paper or synthetic fabric that traps contaminants as the water flows through it. They are easy to clean and can be easily removed by turning a circular locking ring around the filter housing assembly. Cartridge filters typically need to be replaced every 1-2 years depending on how often you use the spa and the size of your filter. Some owners prefer to use a Diatomaceous Earth (DE) filter which is a fine white powder that is made from crushed petrified bones. DE filters are very effective at reducing minerals and other impurities. They can be cleaned by backwashing them which is done by turning a valve to cause the water to flow through the filter backwards and flush away any debris that has built up.

Pressure Side Filtration

Often overlooked in the excitement of choosing a hot tub, the filtration system is one of the most important parts of any spa. Without a good filtration system your hot tub water will quickly turn cloudy. A well designed filtration system can keep your water clean and clear with little effort.

Most modern hot tubs come with what is known as a suction side filtration system. This system works by pulling the water in through a large basket called a “skimmer” and then passing it through a micro filter before returning it back out through the jets. This type of system has some drawbacks however. Because it only skims the surface, any heavier debris like sand will fall to the bottom of the hot tub where it has to be manually removed. Also, suction side systems must run for 12-24 hours each day in order to be effective which adds to your energy costs.

This is why some hot tub companies have developed what is known as a pressure side filtration system. In this system the filter is located outside of the cabinet where it can be easily accessed and monitored with a filter pressure gauge. The advantage of this style is that it requires less maintenance than the traditional suction side filtration and still offers the same or better water quality.

Controlling the Filtration System

Your hot tub is designed with one or more pumps that perform two different functions, filtering and operating the jets. These are controlled by the spa pack which also performs miscellaneous tasks like turning lights, the blowers on and off and providing power for an ozonator. When the ozonator is used it injects oxygen into the water and this enhances sanitizer performance so less sanitizer is required, saving you money on chemical costs.

To keep your filtration system running at peak efficiency, it is important to maintain proper water circulation and run the filtration cycle on schedule. Your filtration system is your main defense against dirt and other contaminants that could foul your hot tub waters, so make sure you don’t neglect it.

Suction side filtration systems require a minimum of 8 hours a day to work effectively and often need to be run for longer to remove heavy debris from the water, which adds to your energy bills. To help cut your costs and to increase efficiencies, many companies have developed what is called pressure side filtration.

These filtration systems use a cartridge that is made up of porous material that allows liquids and gases to pass through but traps unwanted particles, such as dirt and other debris. These filters are easy to maintain and can be cleaned by soaking the cartridge in a solution of household cleaners such as a diatomaceous earth (DE) product.


Getting the most out of your hot tub experience depends on routine cleaning and inspections. One of the most important tasks to complete on a weekly, monthly and yearly basis is filter maintenance.

Cartridge filters use a fine mesh material to remove impurities from the water such as hair, dust, leaves and debris. These filters are easy to clean and require no chemicals. Simply remove them and spray the filter with a hose, let it dry and put it back in place.

If you have a DE (Decaylated Earth) filter, you will need to backwash it regularly by turning a valve that allows water to flow backwards through the filter, flushing away contaminants. It is recommended that you backwash the filter every few days or after each use.

With either type of filter, if you see any buildup on the surface or in the pleats of the cartridge, it is time to clean it. Use a product such as ThermoSpas Filter Cleaner to break apart scale buildup, oily residue and other contaminants to keep your filter working properly. Avoid using household cleaners, laundry detergent or dishwasher soap as these will damage the filter fabric and shorten its lifespan.

It is also a good idea to have a spare filter on hand, so that when you need to clean or rinse it, you can still enjoy the hot tub. Maintaining your Hot Tub Filters will save you money and frustration down the road, not to mention keeping you safe and enjoying your hot tub.

Post Comment