Sand vs. Cartridge vs. DE Pool Filters: Which Is Best?
How each filter type works, how fine it filters, how much maintenance it needs and when to clean or replace the media.
Key takeaways
- DE filters finest (roughly 3–5 microns), cartridge next (10–20), sand coarsest (20–40).
- Clean or backwash when pressure rises 8–10 psi above the clean reading.
- Cartridge filters save water — no backwashing — but need hosing and periodic replacement.
- A filter that is running dirty is the most common cause of hazy water.
The filter removes everything your chlorine has killed and everything the wind blew in. All three common filter types work well when they are sized correctly and maintained. The differences are how fine they filter, how much work they take and how much water they use.
Quick comparison
| Sand | Cartridge | DE | |
|---|---|---|---|
| Filters down to (approx.) | 20–40 microns | 10–20 microns | 3–5 microns |
| How you clean it | Backwash | Remove and hose off | Backwash and recharge DE, periodic teardown |
| Water use | Higher (backwashing) | Lowest | Moderate |
| Media life | Sand every 5–7 years | Cartridges every 1–3 years | Grids last many years |
| Best for | Simplicity, low cost | Water-saving, low-maintenance | Sparkling water, fast clean-ups |
Sand filters
Water passes down through a bed of special filter sand (or an alternative media like glass) and debris gets trapped in the bed. When pressure rises, you backwash — reverse the flow to flush the trapped dirt out to waste. Sand is simple and forgiving, but it does not filter as fine as the other types, so very fine haze can take longer to clear.
Cartridge filters
A pleated fabric cartridge traps debris on its surface. Cleaning means removing the cartridge and hosing it down from top to bottom, with an occasional soak in cartridge cleaner to remove oils. Cartridges filter finer than sand and save the water that backwashing uses.
DE (diatomaceous earth) filters
Grids inside the tank are coated with a fine powder made from fossilized diatoms, which filters extremely fine particles. After backwashing, you add fresh DE through the skimmer. Wear a dust mask when handling DE powder, and check local rules on how backwash water may be discharged.
When to clean any filter
Write down the pressure gauge reading right after a thorough cleaning. That is your baseline. When the gauge reads 8–10 psi higher, it is time to clean or backwash. Cleaning too often actually makes sand and DE filters less effective — a slightly dirty filter traps finer particles.
Signs something is wrong
- Sand in the pool: broken laterals in a sand filter.
- DE puffs from the returns: a torn grid or failed manifold.
- Pressure never rises: torn cartridge or channeling through the media.
- Pressure spikes quickly after cleaning: calcium or oil buildup — time for a chemical clean or new media.
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