Filtration, made simple
Pool Filter Guide: Cartridge vs. Sand vs. D.E.
All three filter types can keep a pool clear when they are correctly sized, maintained, and paired with healthy circulation. The real difference is how they capture debris—and what ownership asks of you.
First principle
Your filter removes particles, not every water problem
Sanitizer helps control germs and algae; the filter removes suspended debris as water circulates. Cloudy or green water may involve chemistry, circulation, algae, or contamination in addition to filtration. Treat the cause instead of assuming the filter is always to blame.
Simple cleaning, no backwash
Water passes through pleated cartridges. You open the tank, remove the elements, rinse them carefully, inspect them, and reinstall them according to the manual.
Durable and familiar
Water passes through a bed of filter sand. A multiport valve reverses flow during backwashing, sending captured debris to waste.
Very fine filtration
Diatomaceous earth coats internal grids or elements. After backwashing or cleaning, the correct amount of filter media must be restored exactly as the manufacturer directs.
Side-by-side
Choose by maintenance style, not marketing alone
Cartridge may fit you if…
- You want to avoid backwashing
- Water conservation matters
- You have space to remove and rinse cartridges
- You are comfortable replacing worn elements
Sand may fit you if…
- You prefer a straightforward backwash routine
- Your property has an approved place for discharge
- Your pool regularly receives larger debris loads
- You value durable, familiar equipment
D.E. may fit you if…
- You prioritize very fine particle capture
- You will follow the recharge procedure carefully
- You can handle and dispose of media safely and legally
- You accept the more involved service routine
Chris’s field rule
A larger, properly matched filter often gives an owner more time between cleanings and less day-to-day resistance. Bigger is not automatically compatible, though—confirm plumbing, pump flow, available space, and the manufacturer’s limits.
Your most useful number
Record clean filter pressure
- Clean the filter correctly. Follow the manual for your cartridge, sand, or D.E. model.
- Return valves and pump settings to normal. The reading is only useful when system conditions are repeatable.
- Write down the pressure. This is your clean baseline—not a universal target from another pool.
- Watch the trend. Rising pressure usually means the system is collecting debris or developing a restriction after the pump. Unusually low pressure can point toward a suction-side or flow problem.
- Service by the manufacturer’s guidance. Do not wait for flow to disappear, and do not clean so aggressively that cartridges or grids are damaged.
Maintenance
What good filter care looks like
Every week
- Read pressure at the same normal pump setting
- Check returns for a change in flow
- Look for drips at the tank, clamp, drain, and unions
- Keep skimmer and pump baskets clear
At service time
- Turn power off and follow the pressure-relief procedure
- Inspect O-rings, clamps, cartridges, grids, laterals, and valve condition as applicable
- Use only the correct replacement media and parts
- Reassemble and leak-check exactly as the manual directs
Never open a pressurized filter
Filter tanks can store dangerous pressure. Shut down the system, isolate power, open the air-relief valve as directed, and confirm the gauge reads zero before loosening a clamp or lid. If you are unsure of the clamp, tank, or relief-valve condition, stop and call a qualified pool professional.
Common mistakes
Avoid these expensive shortcuts
Cleaning without a baseline
If you never record clean pressure, you lose the easiest way to recognize when the system has changed.
Blaming chemistry on the filter
A perfectly clean filter cannot make up for insufficient sanitizer, poor circulation, or active algae.
Using the wrong media
Pool-grade sand, D.E. or approved substitutes, and exact cartridge models are not interchangeable. Follow the label and equipment manual.
Ignoring tank and clamp damage
Cracks, corrosion, stripped hardware, or a damaged pressure-relief assembly need professional evaluation before restart.