Pool Filter: Cartridge vs. DE vs. Sand -- Which Is Right for Your Pool?

Side-by-Side Comparison

Feature	Sand Filter	Cartridge Filter	DE Filter
Filtration fineness	20-40 microns	10-15 microns	2-5 microns
Maintenance method	Backwash when pressure rises 8-10 psi above baseline	Remove and rinse with hose; no backwashing	Backwash + recharge with fresh DE powder
Water usage	High — backwashing uses 200-300+ gallons per cycle	Zero — no backwashing required	Moderate — backwashing uses less water than sand
Upfront cost	Lowest — $200-500 for most residential units	Mid-range — $300-700	Highest — $400-900+
Filter media replacement	Every 5-7 years (sand replacement)	Every 1-3 years (cartridge replacement)	Add DE after each backwash; grid replacement every 5-10 years
Operating pressure	Runs at higher pressure — 15-25 psi typical	Runs at lower pressure — 8-15 psi typical	Runs at lower pressure — 10-16 psi typical
Best for	Budget-conscious; high-debris pools	Low-maintenance; water-conservation areas; smaller pools	Clearest water; competition pools; high-clarity requirements
Chemical handling	None — sand is inert	None — cartridge is inert	DE powder is a respiratory hazard — handle with care, avoid inhaling

Source: Filter micron ratings from manufacturer specifications; filtration industry standards

Sand Filters: The Details

Sand filters are the most common residential pool filter type. They work by passing pool water through a bed of specially graded filter sand (typically #20 silica sand). Debris particles larger than 20-40 microns are trapped in the sand bed; cleaner water returns to the pool.

Maintenance

Backwash when the pressure gauge reads 8-10 psi above the clean baseline reading (not above a fixed number — above your specific filter’s baseline). Backwashing reverses water flow through the sand, flushing trapped debris out through the waste line. One backwash cycle uses 200-300+ gallons of pool water — a consideration in drought-prone regions or areas with water use restrictions.

Sand replacement: filter sand degrades over time as the sharp edges that trap particles wear smooth. Replace sand every 5-7 years. Signs it is time: water that stays cloudy despite correct chemistry and normal filter operation, or pressure that does not return to baseline after backwashing.

Filter sand alternatives

Two common sand alternatives improve filtration fineness without requiring a new filter:

• Zeolite: a natural mineral that filters to approximately 5 microns versus 20-40 for sand. Also has some ammonia-removal properties. Costs 2-3x more than sand. Direct replacement in most sand filters.
• Filter glass (recycled glass): filters to approximately 5-15 microns depending on media grade — finer than standard silica sand, though specific ratings vary by product. Does not harbor bacteria like sand can and requires less frequent backwashing. Costs 2-4x more than sand.

Cartridge Filters: The Details

Cartridge filters use a pleated polyester element to trap debris. Water passes through the pleated fabric; debris is captured on the surface. No backwashing — the cartridge is simply removed and rinsed with a garden hose when pressure rises.

Maintenance

Rinse the cartridge with a hose when pressure rises 8-10 psi above its clean baseline. For heavily used pools or pools near trees, this may be weekly. For lightly used pools, monthly is typical. Soak cartridges in a filter cleaning solution (muriatic acid dilution or commercial cartridge cleaner) once per season to remove oil, sunscreen residue, and mineral deposits that hose rinsing cannot remove.

Cartridge replacement: most residential cartridges last 1-3 years with proper maintenance. Signs it is time: visible tears, crushed pleats, or pressure that does not return to baseline after cleaning.

Where cartridge filters excel

Pools in water-restricted areas where backwashing waste is a concern. Smaller above-ground pools where lower-pressure operation matches the pump. Pools where the owner prioritizes low hands-on maintenance (no backwash valve to operate, no sand replacement). The absence of a backwash requirement does mean no quick pressure relief — cartridges must be physically removed and cleaned rather than running a 3-minute backwash cycle.

DE Filters: The Details

Diatomaceous earth filters use a powder made from fossilized remains of diatoms — microscopic algae — as the actual filter medium. The DE powder coats internal grids inside the filter tank. Water passes through the coated grids, and particles down to 2-5 microns are captured. This is the finest residential pool filtration available — DE filters can remove particles that pass through cartridge and sand filters entirely.

Maintenance

Backwash when pressure rises 8-10 psi above baseline — similar to sand. After backwashing, recharge the filter by adding fresh DE powder through the skimmer with the pump running. The amount of DE to add depends on the filter’s total square footage — typically 1 lb of DE per 10 square feet of filter area. Check the filter manufacturer’s label for the specific recharge amount.

⚠ WARNING:  DE powder is a respiratory hazard. Diatomaceous earth particles are very fine and can cause lung damage with repeated inhalation. Always wear a dust mask when handling DE powder and avoid dry pouring in windy conditions. Wet the powder in a bucket before adding through the skimmer to minimize airborne dust.