Are Hot Tub Filters Universal?

Jennifer Rhodes

By Jennifer Rhodes · Updated

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Are you looking to replace your hot tub filter but don't know where to start?

Hot tub filters are not universal. Not all filters will work in every hot tub. You need to buy the right filter to fit your specific tub.

In this article, you'll learn how to identify what kind of filter you need to buy, how hot tub filters work, and much more to help make sure you get the right filter for your tub—and that you're using it correctly.

What kind of filter does my hot tub use?

The filter market has a huge number of different models, which can be overwhelming if you don't know what you're looking for.

To find the right filter for your spa, you need to either know what the part number is, or measure the exact size of your filter. This information will narrow it down to the filters that will work in your spa.

The part number is found on the top of the filter cartridge. This video shows how you can locate this number:

But while the part number is useful in finding the correct replacement filter, sometimes the number wears off over time. Filters may also have multiple numbers stamped into them that aren't part numbers, so it can be hard to find the right one.

In this case, you need to take the measurements of your filter instead:

  1. First, measure the length of the filter from top to bottom using a measuring tape (in inches).
  2. To figure out the diameter, measure the width of the filter from one edge to the other.
  3. If your filter has a hole on one end, measure the diameter of this as well.
  4. The final step is to identify and measure any threading your filter has as part of the end cap.

This detailed guide from Spa Depot can help you figure out the specific filter your hot tub uses. It shows you exactly how to get the correct measurements and thread size from your filter.

Once you have these measurements, you are almost ready to buy a replacement filter. To find the correct model, you just need to either match the measurements to the right model from a list of spa filters, or use a filter-finding tool.

How do hot tub filters work?

A filter is one of the most important parts of any hot tub. Filters act as automatic spa cleaners, trapping dirt and grime to help keep clean water flowing back to the pump. No one likes sitting in a dirty, mucky hot tub. The filter helps to make sure this doesn't happen.

Hot tub filters are made of folds that trap large particles as water flows around them. These large particles can be leaves, debris, sunblock, or any other unwanted contaminants.

Most filters are manufactured as removable cartridges. Since they are removable, you can easily check and replace them.

However, while a filter cleans your hot tub, it cannot clean itself. So it is up to you to clean the filter on a regular schedule.

Do I need a filter in my hot tub?

It is incredibly important for you to use a filter in your hot tub. All hot tubs require a filter.

Without a filter, running the pump can suck contaminants into the piping, which will clog the pump and reduce the cleanliness and safety of the water.

Due to higher temperatures and frequent exposure to contaminants, hot tubs can become breeding grounds for bacteria and other unhealthy agents if not sanitized properly.

A filter plays an essential part in helping to prevent this, keeping your hot tub fun, safe, and sanitary for you and your guests to enjoy.

How long does a filter last in a hot tub?

You should rinse your hot tub filter at least every two weeks. When it comes to deep cleaning, clean the filter every 1-3 months and replace it after one year.

A regular cleaning routine ensures your filter lasts as long as possible. This will save you money as well as keeping the tub clean.

Don't wait for the filter to break before replacing it though. If you ever notice holes or tears in your filter, replace it immediately—even if it has not been a year yet. Failing to do so can cause dirt and grime to get into your hot tub's mechanical parts, which could damage your spa.

Another important factor regarding the lifespan of a filter is hot tub use. The more often you use the spa, the faster the filter will become clogged. Basically, as soon as you notice any fraying or deterioration in your filter's pleats, it's time for a new one.

How many filters does a spa have?

Many spas have just one filter. However, high-end spas can have up to five filters with an incredibly complex self-cleaning system. The higher the number of filters, the better a spa is at cleaning itself.

As a general rule, the more expensive the hot tub, the more filters it will have too. A higher number of filters can support a higher flow rate, more people, a filter for every intake location, and faster cleaning overall.

However, some hot tubs are designed sub-optimally in regards to filters. They don't have enough filters for the volume of water running through them.

Make sure the number of filters you have is proportionate to the size of your tub. Generally, the more filters, the better.

If you're shopping for a new spa, it's a good idea to check if the number of filters seems like a good match for the size of the spa. This is one sign of a good quality hot tub.

Why does my hot tub have two filters?

If your hot tub has two filters, this is probably a good sign: you have double the filtering power over spas with just one filter.

The most important thing is the ratio between the number of filters in your hot tub and its water volume though. If your hot tub has two filters, but it is a very big hot tub, those filters may not be enough to keep it clean.

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