Cartridge vs Sand vs DE Pool Filters

A pool filter has one job, pulling the fine stuff out of the water, and there are three common ways to do it. The short answer: cartridge for most hot tubs and residential pools, sand for the lowest possible fuss, DE for the clearest water on big pools. This site is built around cartridge filters, so I’ll say up front that I have a soft spot for them, but each type earns its place and the right choice depends on your pool. Here’s the honest comparison.

Sand filters

Water is pushed down through a bed of specially graded sand, which traps debris in the gaps between grains. When the sand loads up, you flip a valve and backwash: reverse the flow to flush the trapped gunk out to waste, then go back to filtering. Sand is the cheapest and most forgiving option, and the media lasts years before it needs changing. The trade-offs are that it filters the coarsest of the three, roughly down to 20 to 40 microns, and every backwash sends a few hundred gallons of water down the drain.

Cartridge filters

Water passes through a pleated fabric element with a lot of surface area folded into a small can. There’s no backwash. You pull the cartridge, rinse it with a hose, soak it now and then, and eventually replace it. Cartridges filter finer than sand, in the neighborhood of 10 to 20 microns, and because there’s no backwashing they waste almost no water, which matters more every year. They’re the easiest type to live with, especially on smaller in-ground pools, above-ground pools, and every hot tub. The upkeep is hands-on cleaning rather than a valve flip, and the cartridges are a wear item you buy every year or two.

DE (diatomaceous earth) filters

A DE filter coats a set of internal grids with diatomaceous earth, a fine powder made of fossilized diatoms, and the water strains through that powder coating. It filters the finest of the three by a wide margin, roughly 2 to 5 microns, so DE gives you the clearest water. In return it asks the most of you: you backwash it, then recharge it with fresh DE powder through the skimmer, and you periodically break it down to clean the grids. The powder needs careful handling, since breathing the dry dust isn’t good for you. It’s the enthusiast’s filter, common on larger pools where water clarity is the priority.

Side by side

So which should you have?

For most hot tubs and a lot of residential pools, cartridge is the sweet spot: fine enough, no water wasted, and simple to maintain. If you have a big pool that collects a lot of fine dust and you want glass-clear water, DE earns its extra work. If you want the least possible fuss and don’t mind slightly coarser filtration, sand is hard to beat. There’s no single right answer, just the one that matches how much upkeep you want to do.

If you already run cartridges, the rest of this site is built for you. You can find your pool filter cartridge by brand and see every cross-reference and Amazon-compatible part, and the guide on cleaning a cartridge covers the upkeep side.