HouseholdRobot.netPool Cleaner Filter Types: Cartridge vs Mesh Bag vs Ultra-Fine
Last updated: May 19, 2026 | 7 min read
Key Takeaway
Robot pool cleaners come with one of three filter systems: removable cartridge baskets (most modern designs), zippered mesh bags (cheaper, harder to clean), or layered ultra-fine + coarse cartridges (premium, captures dust and algae). Filter micron rating — from 200 µm for leaves down to 2 µm for fine silt — determines what the robot actually removes. Owning the wrong filter for your pool's debris is more impactful than picking the wrong robot.
Contents
The Three Filter Categories
- Cartridge / basket filter: A rigid plastic frame holding a pleated screen. Slides out of the top or bottom of the robot. Rinses clean with a garden hose. Used on Dolphin Sigma, Beatbot AquaSense X, Aiper Scuba V3 Ultra, Wybot S3.
- Zippered mesh bag: A fabric bag with a closing zipper. Common on older Dolphin Nautilus and budget cleaners. Holds more leaves but harder to clean — debris pushes through the mesh and the bag itself needs scrubbing.
- Multi-layer cartridge system: Two or three nested cartridges of different fineness. A coarse outer layer catches leaves, a fine middle layer catches dirt, and an optional ultra-fine inner layer captures algae spores and dust. Used on Aquabot X4, Polaris 9650iQ Sport, premium Dolphin models.
Micron Rating: What Gets Captured
A micron (µm) is one thousandth of a millimeter. Pool debris ranges from leaves (10+ mm = 10,000+ µm) down to algae spores (2–5 µm).
| Filter rating | Captures | Misses |
|---|---|---|
| 200 µm (coarse mesh) | Leaves, acorns, large twigs | Sand, dirt, dust |
| 100 µm (standard cartridge) | Above + small leaves, larger insects | Fine dirt, pollen, algae |
| 50 µm (fine cartridge) | Above + most dirt, sand, pollen | Fine algae, talc-like dust |
| 20 µm (ultra-fine) | Above + small algae, dust | Bacteria, dissolved minerals |
| 2–5 µm (premium ultra-fine) | Algae spores, finest dust, pollen grains | Only dissolved chemicals |
Most robots ship with a 50–100 µm cartridge by default. Ultra-fine filters are sold as accessories ($30–80) and clog faster — expect to clean them every 2–3 cycles instead of weekly.
Cleaning & Replacement
Cartridges rinse with a garden hose. Spray from the inside out, never from the outside in — you push debris through the pleats. Soak in mild vinegar solution monthly to remove mineral scale (a thin white film on the pleats is calcium buildup).
- Inspect after every cycle. A 30-second rinse beats a clogged filter degrading suction over the next cycle.
- Replace every 12–18 months for cartridges. Mesh bags last 24–36 months but lose effectiveness much sooner.
- Replace immediately if pleats are torn, the frame is cracked, or you see consistent debris bypass.
Matching Filter to Pool Debris
- Pool under oak/maple trees: Standard cartridge (50–100 µm) is fine for the volume; mesh bag gives more capacity but more cleaning.
- Desert / dust-heavy yards: Fine or ultra-fine cartridges. Coarse filters let dust recirculate.
- Algae-prone pools (warm climates, partial shade): Ultra-fine filters (20 µm or finer) capture algae before it blooms.
- Salt-water pools: Standard cartridge; replace more often as salt accelerates plastic degradation.
- Heavy bather load (kids, sunscreens): Fine cartridge. Sunscreen oils break down into fine particulate that coarse filters miss.
Replacement Filter Pricing
Typical retail ranges for replacement cartridges or cartridge sets (verify with the manufacturer for current pricing in your region):
| Robot | OEM cartridge price | Notes |
|---|---|---|
| Dolphin Sigma | $45–65 | Includes both 70 µm and 20 µm |
| Beatbot AquaSense X | $55–90 | Multi-layer set |
| Aiper Scuba V3 Ultra | $35–55 | Twin pack standard |
| Wybot S3 | $30–45 | Single fine cartridge |
| Aquabot X4 | $40–70 | Twin pack with ultra-fine option |
| Polaris 9650iQ Sport | $60–95 | Two-stage system |