Measuring a hot tub filter

With so many different makes and model of hot tub on the market , it can be tricky to find the replacement filter that you require. This guide will help you find the right filter for your spa. There are a few ways you can find the correct filter and we will break down how to do this by filter code, measurements or make/model. 

By Filter Codehot tub filter code

All hot tub filter manufacturers use reference codes to identify each filter and these are a really easy way to match up replacement filters. Codes are usually printed or engraved on the top or bottom of a hot tub filter. These codes vary in length, style and meaning depending on the manufacturer. Look out for subtle differences, sometimes a code can be one or two characters different and that can mean the filter is different!

How to search by filter code on happyhottubs.co.uk:

  1. Go to www.happyhottubs.co.uk
  2. Locate the search bar at the top of the website.
  3. Search the filter code you require and press enter to search. Example in the image here is HHTAS50F.
  4. Check results for a match
  5. No match? Get in touch, send us some images/information and we will help 

By Measurements

If you cannot source by filter code then measurements are a useful way to check compatibility of a filter. It is a little bit more work than searching a filter code but if done correctly, it will prevent ordering the wrong filter and any hassle that comes with that. There are 3 main aspects to measure/compare; diameter, length and the top/bottom detail.

Measuring Filter Diameter

To measure the diameter, you simply measure across the top of the filter from edge to edge. See image below for guidance. 

hot tub filter diameter

Measuring Filter Length

To measure the filter length, you are aiming to measure top to bottom (excluding the handle and thread). Some suppliers do consider the handle and thread as part of the length but this should be clarified on the product listing when comparing. At Happy Hot Tubs, we look at length without the handle and thread, so just the main body. Here is an image so highlight how to measure the length:

hot tub filter length

Checking the top/bottom

The top of a filter is generally either a closed top, a handle or a hole. Some have dosing systems like the EZ-Pod built-in to the handle but you do not have to use this. The top does not matter as much as the bottom of filter but it is important to check the top of the filter matches in style.

The bottom of a filter is one of the most critical parts. This is usually how the filter is secured within the hot tub itself. Below, we have labelled some of the different types of filter bottom that you can come across. When cross-checking, use a visual comparison and measurements to ensure they match. The list below is not exhaustive but the most common.

Open Hole:

open hole hot tub filter

Coarse Thread (bigger gaps between each turn):

hot tub filter with coarse thread

Fine Thread (smaller gaps between each turn):

hot tub filter with fine thread

Internal thread:

hot tub filter with internal thread

How to find the right filter using measurements

  1. Go to the Happy Hot Tubs Replacement Filters category page
  2. Select ''Filter'' at the top (mobile) or scroll down and look for ''Filter'' on the left (desktop) and select Filter Diameter (mm).
  3. Choose the nearest diameter in mm. As general guidance, smaller is better than larger. A few mm difference is fine.
  4. If you cannot find based on the diameter, clear the filter and select the next nearest diameter. 
  5. To narrow the list down further, filter by Filter Length (mm). 
  6. No match? Get in touch, send us some images/information and we will help.

By Make/Model

Although it might seem simple to just find a filter based on hot tub make/model, models do change filter and manufacturers keep us on our toes! The other factor is that some models have the same name across multipe brands! Even if you do search by make/model and find a good match, it is always worth double checking with someone or cross-checking measurements to be sure it is correct. 

How to search by make/model

  1. Navigate to any page on www.happyhottubs.co.uk
  2. At the top search bar search your model and filter. Example would be ''Propel filter''.
  3. If that does not produce a result, try your brand, IE "Hot Spring filter". This will produce a wider range of results so you will then need to drill-down from there.
  4. No match? Get in touch, send us some images/information and we will help.

FAQs

My current hot tub filter does not have a code, how do I find a replacement?

Take the measurements of your filter and filter by measurements. 

Can I use any filter in my hot tub?

No! Sadly there is nothing standard in our industry. We stock around 50 different types! You will need to use the guide above to find the right cartridge. 

I have found a filter but it is slightly different to my current one, will it be ok?

There is a small acceptable tolerance. If it is a few mm then it should be fine. Unsure? Contact us