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Dolphin Pool & Spa

Filter Cartridge vs. Sand vs. DE: Mid-Season Cleaning Realities

Article #218  |  Monday, August 24, 2026

Pool filter equipment pad in a Minnesota backyard

Images are AI generated and do not depict an actual pool or Dolphin Pool & Spa location.

Late August pushes every filter hard. Kids are back in the pool after school, storms keep dumping pollen and grit, and your filter has been running non-stop since May. Whatever type you own, this is the point in the season where small problems turn into big ones if you skip a cleaning. Here is what each filter type actually needs right now.

Quick check: Watch your pressure gauge, not the calendar. Once pressure rises 8–10 PSI above your clean, just-backwashed reading, it's time to clean the filter—cartridge, sand, or DE.

1 Cartridge Filters

Cartridges load up fast in high-bather-load weeks. A quick hose-off every one to two weeks keeps water flowing, but a hose alone will not strip out body oils and sunscreen buildup. Pull the cartridge and soak it in filter cleaner once a month during peak use. If the pleats look flattened or grey no matter how much you clean them, the cartridge is worn out and needs to be replaced, not cleaned again.

2 Sand Filters

Sand catches fine debris well, but it channels under heavy use—water carves narrow paths through the sand bed instead of filtering evenly. Backwash when your gauge climbs 8–10 PSI, and never backwash on a fixed schedule just because a week has passed. Standard sand loses its sharp edges over a few seasons and starts filtering less fine debris. If you are backwashing more often than you used to with no clear reason, the sand is due for a change.

3 DE Filters

Diatomaceous earth filters give you the cleanest water of the three types, but they take the most attention. Backwash on the same 8–10 PSI rule, then always add fresh DE powder back through the skimmer right after. Once or twice a season, pull the grids and hose them off between the folds where debris hides. Check the grids for tears while you're in there—a torn grid lets DE powder back into the pool and clouds the water.

Heads up: Never skip the DE powder re-add after a backwash—running a DE filter without fresh powder scratches the grids and lets debris straight through. And any time you change filter media of any kind, replace the laterals at the same time. Old, brittle laterals crack under new media and send it straight into your pool.

4 Signs It's Time to Upgrade, Not Just Clean

  • Water looks clean but never sparkles
  • You're backwashing or cleaning more than last year
  • Pressure climbs faster after each cleaning
  • Chlorine demand feels high despite good chemistry
  • Filter media is more than 5–7 years old
  • Fine dust or cloudiness returns within days

If any of that sounds familiar, mid-season is a fine time to upgrade your media rather than wait for a full spring changeout. Here's how our three BioGuard filter media options compare.

Media Filters Down To Best For
Micron1 1 micron Owners who want the clearest water possible, our top upgrade pick
RubySand 3–5 microns Owners who want longer media life than standard sand
Filter Glass* 2 microns Owners who want sand-like performance from a recycled, eco-friendly media
ZeoSand 5 microns Pools with ammonia or chloramine odor issues

*Brand name and micron rating may vary.

Any of these four drops straight into an existing sand filter tank—no new equipment needed. Just remember: new media means new laterals too.

Would rather leave it to us? Bring in your filter and we'll clean it for you—$30 per cartridge filter, or $150 for a full Sta-Rite filter set.

Not sure which filter type is right for you, or whether your media needs a change? Stop in and we'll take a look at your setup and walk you through the best fit—we make pool ownership a joy!

Call Us Now — 763-542-9000

Your Happy Dolphin Pool & Spa Team