How to measure my filter
Allow a variance of +/- 5mm when measuring your spa as old filters alter in size due to expansions & contraction.
Filters have different types of threads:
MPT - The most common type of thread used on filters. This is a FINE threaded end where the threads are close together
SAE - This is a COARSE thread where the threads are much more widely spaced
FEMALE threads - these are where the thread of the filter end is on the inside of the connector end rather than the outside
Some filters manufactured by Pleatco have a removable thread with a male connector placed at the bottom of the filter. You may need to unscrew the filters male connector from your spa if it doesn't come out with the old filter. Most of the filters from other brands are casted in one single piece in such a way that the thread connector will come off with the filter.