When searching for replacement hot tub filters, if you do not have the part number of the quality Darlly filters required, use our quick-to-use comprehensive ‘Find your filter’ helper pages in our online catalogue. By using measurements and by matching the thread type pictures, you should be able to find the quality filter your hot tub deserves.

You can use the dimensions that you have to help get to the required filter. How do you measure a filter? Easy! Follow our easy-to-use guide below showing how to measure the relevant dimensions and identify the thread type, if any. All measurements are in cm.

External diameter

This is the measurement across the filter from edge to edge. This example is 12cm.

Length

Measure the length of the filter but do not include the handle or thread.

Internal / Inside diameter

Thread and fitting types

There are number of different types of fitting and thread types available. Filters can have male and female threads which can be coarse or fine, and possibly tapered.

Photo shows male threads, fine on the left hand side and coarse on the right hand side.

Measure the thread diameter. This is the outer edges of the thread for male thread. For a female thread, measure the inner diameter.

The Fine Thread (MPT) has from 6 – 8 fine twists (Pleatco ends P4 or F2M) whereas the Coarse Thread (SAE) will have as little as only 3 thicker threads (Pleatco ends P3 or F2S). 

Male thread diameter measurement

Female thread diameter measurement

You now have all the dimensions that you will need to help identify your filter.

Just two more items to note now, nearly there!  

What is the original colour of the actual filter fabric? If it is white, it is a normal filter. 

If it is blue, it is probably a Silverstream Antibacterial filter. 

The last item relates to the top of the filter. Does it have a removeable twist-and-pull lid? 

If yes, this will be a Sanistream filter designed to take an in-line dosing pod such as the Darlly Sanistream DL815 SpaPod (suitable for chlorine or bromine tablets) or a Darlly DL816 AquaSPArkle Pod which is ready-filled with sufficient bromine tablets to last you up to a month. 

You should now have all the information you need to identify your filter on the Darlly ‘Find your filter’ pages in the online catalogue.

All genuine Darlly filters have the part number moulded on the end cap (eg “60401”)

Also the label on the outer wrapper will have all details. (Please keep this for next time …..! )

Pleatco and Unicel will also sometimes have the part number on the end cap. Our brochure and website www.darlly.eu contain all of the part numbers to help you. 

However, should you be without any part number after following the identification guide above and using our ‘Find a Filter’ guide using your measurements and brand identities, simply call us on +44 (0)1952 – 580500 we would be delighted to help you. 

If you have any suggestions for hot tub / spa topics or subjects that you would like to read about in our filter care section please get in touch and we will be more than happy to help 

Happy Hot Tubbing!