Pool, Hot Tub & Refrigerator Filter Guides
Short, practical guides to the parts of pool and hot tub filters that trip people up, from measuring a cartridge when the printed number has worn off to making sense of the tangle of cross-reference part numbers. Written by the same person who compiled the data on this site.
Refrigerator Water Filter Numbers, Explained
The box says LT700P, the old filter says AGF80300702. Same filter. How refrigerator filter numbers work and how to read them.
Read the guide →How to Find the Right Water Filter for Your Refrigerator
Read the old filter first, then the full model number, then confirm with the maker. The three steps, and the filter styles you will meet.
Read the guide →How to Measure a Hot Tub Filter Cartridge
The printed number wears off first. Here is how to measure the three things that actually decide which cartridge fits.
Read the guide →Pool and Spa Filter Cross-Reference Numbers, Explained
One cartridge, five part numbers. What Pleatco, Unicel, Filbur, and OEM numbers mean and how they line up.
Read the guide →How Often Should You Replace a Filter Cartridge?
One to two years is the rough answer. The pressure gauge is the honest one. Here is how to tell when a cartridge is actually spent.
Read the guide →How to Clean a Pool or Hot Tub Filter Cartridge
The 45-degree rinse, when to soak, and the two shortcuts that quietly ruin cartridges (one of them is the pressure washer).
Read the guide →Cartridge vs Sand vs DE Pool Filters
Three ways to filter a pool, compared: how fine each one gets, what each costs you in upkeep, and which fits which pool.
Read the guide →Are Generic Filter Cartridges as Good as OEM?
Usually yes, sometimes with a catch. Where generic cartridges match the original, where they can differ, and how to buy a good one.
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