Pool filters come in three main types: sand filters (low maintenance, 5-7 year lifespan), cartridge filters (easy cleaning, 1-2 year replacement), and DE filters (finest filtration, requires backwashing every 4-6 weeks).
Pool filtration is the backbone of clean, healthy swimming water. The three main filter types each offer distinct advantages:
Your choice depends on budget, maintenance preferences, and desired water quality. Understanding how pool filters work helps you make the right decision for your specific needs.
Sand filters use specially graded silica sand as the filtering medium. Water flows down through the sand bed, which traps debris and particles. The sand grains create a physical barrier that captures contaminants as small as 20-40 microns.
The filtration process relies on the sand bed becoming slightly "dirty" to work optimally. A thin layer of captured debris actually improves filtration efficiency by creating smaller pathways for water to flow through.
Weekly:
Bi-Weekly to Monthly:
Quarterly:
Every 5-7 Years:
Cartridge filters use pleated polyester or paper-like material to strain particles from pool water. The large surface area created by the pleated design allows for fine filtration while maintaining good water flow rates.
Multiple cartridges typically work together in a housing, and water flows through the filter media from outside to inside, trapping debris in the pleated material.
Weekly:
Bi-Weekly to Monthly:
Quarterly:
Annually or Bi-Annually:
DE filters use diatomaceous earth, a fine powder made from fossilized diatoms, as the filtering medium. The DE powder coats fabric-covered grids inside the filter housing, creating an extremely fine filtering surface.
This biological filter media can trap particles as small as 2-5 microns, providing the clearest water of all filter types. The microscopic porous structure of DE creates an incredibly effective physical barrier.
Weekly:
Monthly (or as needed):
Seasonally:
Every 1-3 Years:
Light Use Pools: Cartridge filters work well for pools with minimal bather loads and moderate debris.
Heavy Use Pools: Sand filters handle high bather loads and debris better with less frequent maintenance.
Premium Water Quality: DE filters provide the clearest water for those prioritizing appearance.
Initial Cost:
Annual Operating Costs:
Sand Filters: 15-30 minutes monthly for backwashing
Cartridge Filters: 30-60 minutes bi-weekly for cleaning
DE Filters: 45-90 minutes monthly, plus seasonal deep cleaning
Your filter choice affects pump selection and operation. Understanding when you need a new pump helps ensure proper system matching.
Variable speed pumps work excellently with all filter types, providing energy savings and extended filtration cycles that benefit water quality.
Filter efficiency directly affects chemical usage and water balance:
Proper filtration supports your overall chemical program, whether you're maintaining traditional chlorine levels or managing a saltwater system with cyanuric acid.
Symptoms: Cloudy water, visible debris, algae growth
Solutions:
Sand/DE Filters: Backwash when pressure exceeds clean pressure by 8-10 PSI
Cartridge Filters: Clean cartridges when flow noticeably decreases
If filters require cleaning/backwashing more frequently:
Sand Channeling: Replace old sand, check for broken laterals
Torn Cartridges: Replace immediately to prevent bypass
DE Bypass: Inspect grids for tears, verify proper DE application
For pools requiring winterization, follow proper winterization procedures:
Professional consultation helps with:
If standard maintenance doesn't resolve problems:
Glass Media: Replacement for sand with finer filtration and longer life
Zeolite: Natural mineral media with ammonia removal properties
Polyester Filter Balls: Reusable alternative to sand for some applications
Some installations combine filter types:
Modern filter systems can integrate with:
Cleaning frequency depends on filter type: sand filters need backwashing every 2-4 weeks, cartridge filters require cleaning every 2-4 weeks, and DE filters need backwashing monthly or when pressure rises 8-10 PSI.
Usually yes, but verify compatibility with your pump and plumbing. Some upgrades may require different plumbing connections or pump sizing adjustments.
All filter types work with saltwater systems. Saltwater pools still need proper chemical balance, and filter choice depends more on maintenance preferences and water quality goals.
Filter replacement timing varies by type: sand every 5-7 years, cartridges every 1-2 years, and DE grids every 1-3 years depending on condition.
Never run your pool system without proper filtration. Even brief periods without filtration can lead to rapid water quality deterioration and potential equipment damage.
Cloudy water often requires both proper filtration and chemical treatment. Test water chemistry and shock if necessary, as filtration alone may not resolve chemical imbalances.
Effective pool filtration works best as part of a comprehensive maintenance program:
Remember that understanding how your specific filter works helps you maintain it properly and troubleshoot issues effectively. Regular maintenance prevents most problems and ensures years of reliable filtration performance.
Was this guide helpful?
Try our free pool calculators and tools to help diagnose and fix your pool problems.
Browse Pool ToolsSLAM calculator, pH calculator, salt dosing & more
Pool Repair Question