Replacement cartridges are sold under dozens of brand model numbers, but housings only care about three measurements. Hydrana cartridges are not made by Pentek, Culligan, GE or 3M, and we do not claim to be those brands — we make cartridges in the standard sizes those housings use. Measure your old cartridge, match the size class below, and order the Hydrana cartridge with the same length, diameter and micron.
Step 1: Measure — length, diameter, micron
Length: top to bottom of the old cartridge — almost always 10 inch or 20 inch (some nominal 9.75 inch cartridges are sold and searched as 10 inch class). Diameter: across the end cap — 2.5 inch means a standard slim housing, 4.5 inch means a Big Blue style housing. Micron: printed on the cartridge, its end cap, or its packaging. Matching the cartridge you already use is the safest starting point.
Step 2: Common model numbers, grouped by size class
10 inch x 2.5 inch standard class: the size family of cartridges such as the 3M Aqua-Pure AP110 / AP111 class and the Culligan P5 / P5A class — slim 10 inch cartridges for standard housings, commonly in 5 micron. If your old cartridge is one of these, order a Hydrana 10 inch / 2.5 inch cartridge in your micron.
10 inch x 4.5 inch Big Blue class: the size family of the Pentek WP5BB97P (a 10 x 4.5, 5 micron string-wound class cartridge) and of the Pentek WP25BB97P / Culligan CW25-BBS class (10 x 4.5, around 25 micron). Hydrana makes the 10 inch / 4.5 inch size in 1, 5, 10, 20, 30, 50 and 100 micron; for a 25-micron-class replacement, choose 20 micron for slightly finer filtration or 30 micron for slightly longer life.
20 inch x 4.5 inch Big Blue class: the size family of the Pentek DGD-5005-20 class (20 x 4.5, 5 micron) and of large high-flow whole-house cartridges in the GE FXHTC class. Order a Hydrana 20 inch / 4.5 inch cartridge in your micron — this is the premium, longest-life replacement size.
10 inch standard class (pleated originals): cartridges in the GE FXWPC class are 10 inch standard-housing cartridges, commonly around 30 micron in pleated form. The Hydrana equivalent by fit is a 10 inch / 2.5 inch string-wound cartridge in 30 micron — same housing fit, depth-filtration construction.
Step 3: When the numbers do not match your cartridge
Model numbers change, private labels multiply, and a previous owner may have installed anything. Your measurements always win over any chart — including this one. If your micron is not printed, start with 5 micron for general whole-house use or 20 micron for visibly gritty water, and adjust after one cycle. Then shop by size: Big Blue Sediment Filters for 4.5 inch housings, Sediment Filter Replacement Cartridges for everything, or 5 Micron Sediment Filters for the most common rating. Every Hydrana cartridge is manufactured in the USA and made to order in the exact size and micron you choose.