Specification

1. Measure the outside diameter (O.D.) of the cartridge.
2. Measure the cartridge length. INCLUDING the end
caps BUT EXCLUDING any handles or other
extensions.
3. Identify the type of end cap your lter cartridge has
(see next page). If the top and/or bottom is “open”,
measure the inside diameter (I.D.) of the top and/or
bottom.
How To Measure A Filter Cartridge
NOTE: Measuring your spa or hot tub’s lter cartridge is an exact measurement in inches. The
measurements can be down to the +/- 1/32 of an inch measurement. For example you may
measure the outside diameter (O.D.) of your lter aand think it is a measurement of 5” O.D.
when the actual measurement listed for your lter could be 4 15/16” O.D.
O.D.
End Caps
Length
Measurement
I.D.