Hot Tub Filters: How Often to Clean and When to Replace

Depending on who you ask or which site you visit, you’ll get different advice on when it’s time to change out your hot tub filter. Having used spas for many years, this is what I’ve learned.

Hot tub filters are designed to last for one year. The exact amount of time a hot tub filter lasts depends on how often you use your spa. Even if you don’t use your hot tub very often, you should replace the filters at least once a year to avoid a build-up of bacteria and ensure that the water is safe.

How often should I clean my hot tub filter?

Maintaining a regular cleaning routine is especially important with filter cartridges as they play a key role in keeping your water clean and pure.

Hot tub filters need to be rinsed with fresh, clean water at least once a week. As well as weekly cleans, you should perform a monthly rinse using a chemical spray. Every 3 months, the filter needs to be left in chemical soak for 24 hours to ensure a deep clean.

Regularly rinsing and cleaning helps to prolong the life of the filter and ensures that it continues to work efficiently so that the water is safe for bathing.

The two main factors that influence the frequency with which you need to clean the filter are usage and climate. The more you use your hot tub, the harder the filters have to work, so the more frequently they’re going to need to be cleaned.

The other factor is the climate in which you live. The hotter it is, the more you’ll need to clean the filter. If your hot tub sees heavy use (used 4+ times per week), you may need to carry out cleaning on a more regular basis.

Weekly rinse

Rinsing the filter once a week prevents a build-up of debris that can cause clogging. It also stops the spa chemicals from eating away at the filter fibers.

Remove the filter from the filter well and rinse thoroughly with fresh water. Make sure to spread the pleats apart to remove all the dirt and debris.

Rinsing can be carried out in the sink, bathtub, or outside using a garden hose fitted with an inline pre-filter. Never clean your hot tub filter with a pressure washer as it’ll damage the fibers. Once the pleats are clean and free of dirt, you can replace the filter back into the well.

Monthly chemical rinse

Once a month, it’s necessary to perform a chemical rinse. This involves spraying the filter between the pleats with a specially formulated chemical spray and allowing it to sit for 15 minutes while it gets to work.

I like to use this particular filter cleaner as it comes ready in a handy spray bottle so you don’t need to mess around transferring the liquid.

Once the 15 minutes are up, rinse off the chemical solution thoroughly and ensure that all the pleats are free of dirt and debris just like you would do during a weekly clean.

Never use detergents to clean your filter cartridges as they can cause foaming. Foaming usually requires having to drain all of the water in your hot tub.

While it’s possible to use bleach to clean a hot tub shell, never use it on filter cartridges as it destroys the fibers.

Quarterly chemical soak

Once every three months, you’ll need to perform a deep clean by placing the filter cartridges in a powerful chemical soak.

It’s ideal to carry out a deep filter clean at the same time you drain the water from your hot tub.

It’s recommended to drain the water at least every 3 – 4 months, but a more frequent drain may be required if your hot tub sees a lot of use and is used by many bathers.

Knowing how often you should drain and refill your hot tub with fresh water is important if you want to avoid a build-up of bacteria, so check out my guide to calculating drainage frequency for your usage habits.

According to the directions on the bottle, dilute the chemical soak with water in a large, clean bucket. The bucket needs to be large enough to fully submerge the filter.

Place the filter inside the bucket and allow it to soak in the solution for 24 hours. After 24 hours, rinse thoroughly, ensure the pleats are free of dirt, and leave to air dry before placing back into the filter well.

When you’re carrying out a chemical soak, it’s worth having an extra filter on standby for a couple of reasons. Firstly, so that you can install the backup to enjoy your hot tub while the dirty filter is being cleaned.

The second reason to have a backup filter is so that you’re prepared for when it’s no longer possible to get the current filter clean. You should never use a hot tub without a filter, so having an extra one on hand means you won’t have to wait until the new one is delivered.

What will happen if I don’t clean my hot tub filter?

Cleaning and maintaining your hot tub filters is essential so that the hot tub can function properly. Cleaning the hot tub filters every week prolongs their life and ensures that the water is kept sanitary.

The filters play a key role alongside the sanitizing chemicals to keep the hot tub clear and free of bacteria. When a filter is allowed to become dirty, the fibers become clogged, making them unable to properly filter the water.

If the filters aren’t able to filter any debris in the water, it can make its way into the heater, pumps, and other components of the spa, causing damage and potential failure.

Another issue caused by clogged filters is low flow. This puts a strain on the pump, as well as increasing the heating time and decreasing the pressure coming through the jets.

6 signs your hot tub filter needs changing

While a regular maintenance routine will prolong the life of your filter, sooner or later it’ll need to be replaced.

Even if you don’t use your hot tub all that often, the filter still needs to be replaced at least once per year. The reason being is that water is constantly cycling through the filter, even when the hot tub isn’t in use.

Over time, the fibers get broken down, allowing more contaminants and larger and larger particles to pass through, causing damage to the pump.

Although cleaning is absolutely necessary to ensure proper filtration, the rinsing and cleaning stretch apart the fibers, reducing the amount of dirt that they’re able to trap and filter out.

In fact, by the time you’ve cleaned the filter a dozen times, it could be allowing as much as twice the volume of contaminants and particles to slip through compared to when it was new.

Another possible sign that a filter needs changing is that the water isn’t clear. If the filter is clogged and dirty, the water isn’t able to flow properly, causing the water to cloud up.

Saying that, cloudy water may also be sign of a chemical imbalance, so make sure to test the water first to confirm whether or not the cause is the filter.

Another sign is when you notice a difference between the pressure of the water flowing into the filter and the pressure flowing out, then this is also a sign that it’s clogged up. Performing a chemical soak might resolve the problem, but it’ll need to be replaced if it doesn’t.

And if you’re having to rinse the filter with a chemical spray every two weeks instead of monthly in order to maintain water clarity and proper filter pressure, then this is a sure sign that it’s time to change out the filter.

Finally, the filter may have developed a leak or crack. While this doesn’t happen all that often, you must replace the filter as soon as possible if this is the case.