Swimming Pool Filters: Sand, Cartridge & D.E. Compared

Your pool filter is the kidney of your circulation system—removing particles, algae, and contaminants to keep water clear and safe. The three main types differ in filtration fineness, maintenance, and cost. Here's how to choose.

1. Sand Filters

How They Work

Water enters a tank filled with #20 silica sand (0.45–0.55mm). Particles down to ~20–40 microns are trapped. Backwashing (reversing flow) flushes dirt to waste.

Pros

• Lowest upfront cost.
• Simple operation (multiport valve).
• Sand lasts 5–7 years.
• Handles high flow rates.

Cons

• Least fine filtration (20–40 microns).
• Backwashing wastes water (hundreds of gallons).
• Sand can channel (water bypasses media).
• Weekly backwash needed during season.

2. Cartridge Filters

How They Work

Water passes through pleated polyester cartridges (like a car oil filter). Traps particles down to 10–15 microns. Clean by removing and hosing off.

Pros

• Finer filtration than sand.
• No backwashing = water savings.
• Lower pump pressure = energy savings.
• Compact footprint.

Cons

• Cartridges replace every 2–3 years ($50–$150 each).
• Cleaning is manual (hose off pleats).
• Not ideal for very high flow rates.
• Oil/sunscreen clogs pleats; need chemical cleaner periodically.

3. Diatomaceous Earth (D.E.) Filters

How They Work

Grids coated with D.E. powder (fossilized diatoms) filter down to 2–5 microns—near drinking-water clarity. Backwash to clean; recharge with fresh D.E.

Pros

• Finest filtration available.
• Removes microscopic algae, bacteria, oils.
• Polishes water to exceptional clarity.

Cons

• Highest cost (unit + D.E. powder).
• D.E. is a respiratory hazard (wear mask).
• Backwash + recharge process more involved.
• Some areas restrict D.E. disposal.
• Grids can tear; replacement costly.

Comparison Table

Factor	Sand	Cartridge	D.E.
Filtration (microns)	20–40	10–15	2–5
Initial Cost	Low	Medium	High
Ongoing Cost	Low (sand 5–7 yr)	Medium (cartridges 2–3 yr)	High (D.E. each backwash)
Maintenance Effort	Low (backwash)	Medium (clean cartridges)	High (backwash + recharge)
Water Waste	High	None	High
Best For	Large pools, low maintenance	Most residential pools	Clarity-obsessed, small–med pools

Installation & Sizing Tips

• Match filter flow rate (GPM) to pump output. Oversize filter = longer cycles, less cleaning.
• Plumb with unions for easy service.
• Pressure gauge mandatory—clean when 8–10 psi above clean baseline.
• Follow local codes for backwash discharge.

Recommendation

For most homeowners, a **large cartridge filter** (300–400 sq ft) hits the sweet spot: excellent clarity, no water waste, manageable maintenance. Sand if you prioritize simplicity and have a large pool. D.E. if you demand the absolute clearest water and accept the work.

For filters and expert advice, visit Pool Supply For Less.