Equipment Guide
Pool Filter Buying Guide
Sand vs. cartridge vs. D.E. — filtration quality, maintenance requirements, and which is right for your pool. No fluff, just the answer.
Filter Types
Three Types Of Pool Filters
Included With Most AG Kits
Sand Filter
Filters down to 20–40 microns. Lowest maintenance — backwash when pressure rises. Replace sand every 5–7 years. Reliable and simple.
Low maintenance — just backwash
Sand lasts 5–7 years
Very reliable — few moving parts
Coarsest filtration — 20–40 microns
Wastes water when backwashing
Best for Most Pools
Cartridge Filter
Filters down to 10–15 microns — noticeably cleaner water. No backwashing, no water waste. Remove and rinse cartridge when pressure rises. Replace every 1–3 years.
Finest filtration — clearest water
No backwashing — no water waste
Good for areas with water restrictions
Cartridge needs periodic replacement ($20–$80)
Commercial Grade
D.E. Filter
Filters down to 2–5 microns — crystal clear water. Most maintenance-intensive. Requires diatomaceous earth powder and periodic disassembly.
Finest possible filtration
Most maintenance-intensive of the three
Requires D.E. powder after every backwash
Highest cost and most complex
Sizing
How to Size Your Filter
Your filter flow rate must match or exceed your pump output. Undersized filters wear out faster and work too hard.
15' Round
Approximate Gallons: ~5,300 gal
Min Sand Filter: 16" sand filter
Min Cartridge Filter: 50 sq ft cartridge
18' Round
Approximate Gallons: ~8,500 gal
Min Sand Filter: 19" sand filter
Min Cartridge Filter: 75 sq ft cartridge
21' Round
Approximate Gallons: ~10,400 gal
Min Sand Filter: 19" sand filter
Min Cartridge Filter: 100 sq ft cartridge
24' Round
Approximate Gallons: ~15,300 gal
Min Sand Filter: 22" sand filter
Min Cartridge Filter: 150 sq ft cartridge
27'-30' Round
Approximate Gallons: ~20,000 gal
Min Sand Filter: 24" sand filter
Min Cartridge Filter: 200 sq ft cartridge
Good to Know
Your kit includes a filter. All Poolzilla Above Ground kits ship with a sand filter matched to your pool size. Use this table when replacing or upgrading.
Cartridge Maintenance
When To Clean Vs. Replace Your Cartridge
Clean When...
Filters down to 20–40 microns. Lowest maintenance — backwash when pressure rises. Replace sand every 5–7 years. Reliable and simple.
Filter pressure rises 8–10 PSI above starting pressure
Water flow from returns decreases noticeably
Every 2–4 weeks during heavy use season
After a large debris event like a storm
Remove the cartridge, rinse with a garden hose from top to bottom between pleats. Let dry before reinstalling if possible.
Replace When...
Filters down to 10–15 microns — noticeably cleaner water. No backwashing, no water waste. Remove and rinse cartridge when pressure rises. Replace every 1–3 years.
Pressure remains high even after thorough cleaning
Pleats are torn, frayed, or collapsed
End caps are cracked or the core is deformed
After 1–3 seasons of regular use
A worn cartridge wastes energy and lets particles through. Search by your filter model number for replacement cartridges.
Here to Help
Need A Replacement
Cartridge Or Filter?
Tell us your filter model number or pool size — we will find the right cartridge and get it shipped fast.