How do I measure my spa filters / swim spa filter cartridge? (Step by step guide)
Changing your spa filters periodically will help keep your spa water clean and can mean that you’ll use less chemicals to sanitise your water.
If your filters are clogged or worn, they won’t be doing their job properly and may be reducing the flow of water through your spa, putting undue stress on your pumps and causing water quality problems.
There are hundreds of different filter cartridges on the market, so choosing the right one for your spa can be a challenge.
In this article we’ll discuss how to measure and identify your spa filters so you can get the right replacement the first time!
How do I measure my spa filters?
Step 1. Measure the overall length
Using a tape measure, measure the overall length of the filter cartridge. This measurement should include the end caps but not any protruding threads, handles or strings or any other attachments that are fixed onto the end of the cartridge.
If your cartridge is hollow in the centre, you can insert the tape measure inside the internal hole and take the internal length. You should get this measurement as close as you can with a margin for error of +/- 1mm.
Step 2. Measure the outside diameter (width)
The next measurement you need to get is the full outside width (diameter) across the filter (top or bottom is fine). Try and get this measurement as close as you can within about 1mm ideally.
Try and get the measurement accurate to within 1mm to ensure you get a replacement cartridge to ensure you get the best possible fit for your replacement.
Step 3. Measure the inside diameter of the opening.
Not all cartridges have a hollow centre section, so this may not be relevant. If there is a hollow middle section, then measure the inside diameter of this hole.
If the top is closed, then make a note of any design features on the top such as a handle or any other fixtures,
Step 4. Identify the type of fitting on the base of the filters (fine thread, coarse thread, camlock etc)
Camlock / bayonet type base locks into place
Fine thread on base of filter (8-9 threads visible)
Coarse thread on base of filter (only 3 threads visible)
Once you have these measurements and details, you can send them to us and we can assist you with finding the right replacement filter. Or browse from the range of spa filters available online to find the best match.
You can use the ‘search filter’ function on the left of the screen to help you narrow down the search to the closest match. Click ‘Filter By Length’ first, then select the range that is closest to the length measurement that you took in the step above.
You can also filter by the type of base on the filter, by selecting ‘Filter by Bottom’ to choose whether you want a threaded or non-threaded base.
Are all spa pool filters the same?
Absolutely not! There are literally hundreds of different filters on the market of all shapes and sizes! You’ll need to measure your existing filters and provide as much information as possible to your filter supplier, so you can get the correct replacement.
Most filters are cylindrical in shape with pleated filter media, but the dimensions vary depending on the make and model of your spa pool. If you have your spa owners manual available, you can consult that for the specifications, otherwise you’ll need to measure your filter following the steps in this article.
The image below shows a range of the different types and sizes of spa filters available.
Where is the filter located in a spa pool?
As a general rule, the filter in a spa is located in a filter box which is usually mounted in one of the corners or on the side inside your spa. Some spas will also have a top entry filter housing which is accessed from one of the top edges of your spa.
How many filters do spa pools have?
Spa pools generally have between 1 and 3 filters. The exact number depends on the size and model of the spa. Smaller spas up to around 1000L in volume will generally have 1 or 2 filters. Spas over 1100L in volume generally have 2-3 filters.
My filter has a handle at the top, does the replacement filter need a handle?
No, you do not need a handle as long as the replacement filter meets all other requirements (length, width & connection)
How long is a spa pool filter good for?
It is recommended to change your spa filters approximately every 12-18 months. In spas with heavy usage or with water quality issues, you may need to change the filters more often. Purezone filters should be replaced every 3-4 months, depending on bather load.
Should I soak new spa pool filters?
It is not necessary to soak new spa filters, you can install them into the filter housing in your spa and start using them right away.
How do I know what size my spa pool filter is?
To identify the size of your spa filter, you should remove the filter from it’s housing and measure the length and diameter.
Can I run my spa without a filter?
No you should never run your spa without a filter installed. This can allow debris to be sucked into your spas plumbing, causing blockages and damage to your equipment. It can be costly to repair a pump for example if a leaf or dirt has been sucked into it.
We recommend turning off your spa when you remove your filters to clean or replace them. Only turn the spa back on when you have replaced the filters.
Got more questions?
Talk to us on live chat, or email us your spa filter questions and we'll be happy to help!
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