How to find a replacement cartridge for your pool or spa ? If you already know your filter cartridge's part number or the replacement number, you can use the search the part number on our product page to quickly confirm whether the filter is compatible. If you do not know the replacement part number for your cartridge, then choosing the right cartridge can be accomplished by measuring your existing one. Use the following steps as a guide: Measure the outside diameter of the cartridge in inches (+/- 1/16th).Measure cartridge length from end cap to end cap (+/- 1/16th). Exclude any handles or extensions.Identify the correct top and bottom type. If the top and/or bottom is open, measure the inside diameter of the opening (+/- 1/16th). If the end cap is closed make note of its identifying features (i.e. Handle, Cone, etc.).
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