The short answer
All three keep water clear when sized right. Sand is the simplest: backwash when pressure rises. Cartridge filters trap finer particles and don't backwash, so they waste less water; you hose the cartridge off. DE filters trap the finest particles but need DE powder added after each backwash.
Side by side
| Sand | Cartridge | DE | |
|---|---|---|---|
| Filters down to (roughly) | 20-40 microns | 10-20 microns | 3-5 microns |
| Cleaning | Backwash | Hose off the cartridge | Backwash, then add DE |
| Water use | Highest | Lowest | Medium |
| Replacement | Sand every few years | Cartridge every 1-3 seasons | Grids over time |
Examples we cover
Sand: the Hayward ProSeries 24 in. Above-ground cartridge combos like the Intex Krystal Clear 2,500 GPH take Intex cartridges; replacement cartridges such as the Pleatco PA120 fit in-ground cartridge filters.
Size it to the pump
Whatever the type, the filter's maximum flow must be at least the pump's actual flow. The pump and filter calculator lists filters rated for your flow.
Products mentioned
Questions readers ask
Which pool filter is easiest to maintain?
Sand: you backwash when the pressure gauge rises 8 to 10 psi above clean, and replace the sand every few years.
Can I switch from sand to cartridge?
Yes, by replacing the filter; the pump and plumbing usually stay if the new filter is rated for the pump's flow.