To identify a replacement pool filter cartridge, record the filter’s full model from its outside label and match it to the manufacturer’s applicable replacement-parts list. Then confirm the cartridge part number and how many elements the order includes. Keep those details together before comparing offers.
This guide helps you prepare a parts inquiry. It does not determine whether your filter needs new cartridges. If the concern is pressure that stays high after cleaning, start with the existing high-pressure diagnostic guide and request an assessment before ordering.
Read the outside label without opening the filter
Photograph the outside model label only if it is safely visible from where you can stand clear of the equipment. Capture the brand, complete model, product number and any serial or date information. Keep the whole label in the picture so a clipped suffix does not get lost.
If the label is faded or inaccessible, say so. A past installation invoice or equipment record may help the technician narrow the search. Do not guess a model from the tank’s color or substitute the nearby pump’s label.
Leave the filter closed. Do not loosen the clamp, open the tank, operate valves or start equipment to gather information. Pool filters contain pressure, and trapped air can cause violent lid separation. Pentair recommends professional filter maintenance. Leave internal inspection and measurements to a qualified pool professional.
Keep the tank, filter area and cartridge numbers separate
Write each identifier beside what it describes. A number in a seller’s listing can refer to the complete filter, one replacement element or a package of elements. Ask the seller to clarify which item the price covers.
Manufacturer example: Pentair identifies the FullFloXF C620 as product 160448, a four-cartridge filter with 620 square feet of total filtration area. The complete-filter product number is different from the replacement-element numbers.
The C-Series manual’s replacement-parts list, printed page 14, lists ULTRA-A18 for a single cartridge and ULTRA-A18-PAK4 for the four-cartridge set. This example uses manual 170069, Revision D, dated August 20, 2025. It illustrates a manufacturer lookup, not a Redzone customer’s equipment or a recommendation for another model.
Ask the supplier or technician to confirm the applicable manual and current replacement before purchasing. Keep that confirmation with the quote, especially if the proposed number differs from an older invoice.
Use this three-field parts-identification card
- Outside label
- Brand, full model and product number. Add serial or date details if safely visible.
- Matching source
- Manufacturer manual, revision and parts page. Ask the technician to confirm it applies.
- Proposed replacement
- Replacement manufacturer, exact part number and quantity. Record who confirmed the match.
Copy these three fields into your notes or print this page. Leave an unknown field blank and ask for help with it; a plausible-looking guess can follow a quote all the way to an order.
Why a similar-looking element needs another check
Use listing photos and dimensions as cross-checks after the model match. Ask for explicit compatibility with your equipment rather than relying on a photograph, an approximate measurement or the same square-footage number.
For a proposed substitute, request the replacement manufacturer’s written cross-reference to the original part. Have the technician confirm the fit, including the end connections and how the element seats. Do not open the filter to measure a cartridge yourself.
Ask about the surrounding parts, too
The C-Series parts list separately identifies the top manifold, its O-ring and support pipes. Ask the technician whether those components need attention during the assessment and whether the quote includes any additional parts. Their presence in a diagram does not establish their condition in your filter.
For the service options, see filter repair and element replacement. Ask what the inspection found, which components would be retained and what the proposed work is intended to fix.
What to include in your filter inquiry
For Katy and Fulshear-area service, including West Katy and Cinco Ranch, include your neighborhood and ZIP so Redzone can confirm coverage for your address. A ZIP such as 77494 does not define every city or neighborhood boundary.
Use the message box on the filter assessment request form for the outside-label text, the symptom and when it began. Mention any recent cleaning or equipment changes. Have an outside-label photo ready and ask how to share it; the form accepts text details. An unreadable label is a reason to request identification help before buying.
Sources checked October 11, 2026. The manufacturer example above is for identification only; confirm compatibility and availability for the equipment being quoted.