A backwashing sediment filter is a tank of media that traps particles as water passes down through it and cleans itself by reversing the flow to drain. The tank and the control head are much the same whatever goes in them, so the media choice is where the performance difference actually sits, and it is decided by what size of particle needs catching.
Graded sand and gravel
The traditional bed: coarse gravel at the bottom supporting the media and preventing it entering the underdrain, rising through progressively finer layers to fine sand at the top. It removes sand, grit, rust particles and coarser silt well, lasts for years, and is inexpensive to fill. Its ceiling is fineness: finer silt and clay largely pass, and where the complaint is cloudiness rather than grit a sand bed can disappoint while working exactly as designed.
Zeolite
Natural zeolite has a rough, highly porous grain that traps smaller particles than sand of the same size, and it does so at a lower weight per tank, which matters where floor loading or handling is a concern. It suits water carrying fine silt that sand passes, and it backwashes conventionally. It is more expensive per fill than sand and is worth it where the particle size is the problem. Note that this is filtration zeolite, not the manganese treated version used for iron.
Multi media beds
Layering media of different densities, typically anthracite over sand over garnet, gives a bed that catches a wider particle size range in one vessel: the lighter coarse layer takes large particles at the top and the denser fine layers catch progressively smaller ones below. Backwashing reclassifies the layers by density so they reform in the right order, which is why the rinse stage matters more here than in a single media bed. It costs more and performs correspondingly better.
What the tank needs whatever the media
A flow rate high enough to fluidize the bed for backwash, which on a low yield well can exceed what the borehole delivers and is a real design constraint. A drain that will take that flow with an air gap. Headroom to service the control head. And a centrifugal separator ahead of it where the well makes coarse sand, plus a cartridge stage after it to polish what the bed passes. Our sediment filter guide covers sizing to a well's yield.
Questions people ask about backwashing sediment filter
Which media catches the finest particles?
A multi media bed, layering densities to catch a range in one vessel. Zeolite filters finer than sand at lower weight.
Why does the rinse stage matter?
It reclassifies the media by density so the graded layers reform correctly. A disordered bed channels and treats very little.
What limits a backwashing filter on a well?
The flow needed to fluidize the bed, which on a low yield borehole can exceed what the well actually delivers.
Do I still need a cartridge after it?
Usually, to polish the fine material the bed passes, with a centrifugal separator ahead where the well makes coarse sand.