Harmsco (HB-20-0.35W) 20"X4.5" Big Blue "Calypso Blue" Pleated Sediment 0.35 Micron Filter
HB-20-0.35W Calypso Blue Pleated Polyester Cartridge
20" x 4.5" pleated sediment filter with 0.35 micron rating for whole-house and light industrial applications. Built to last, designed to be cleaned and reused.
Premium filtration with long-term economy
Sub-Micron Sediment Removal
0.35 micron pleated polyester media captures fine silt, sand, rust, and particulate that pass through standard sediment filters
Cleanable & Reusable
Unlike disposable cartridges, the Calypso Blue can be backwashed or rinsed clean in most applications, reducing long-term replacement costs
High Dirt Holding Capacity
Pleated construction offers more surface area than wound or spun cartridges, extending time between cleanings even in heavy sediment loads
Wide Temperature Range
Plastisol PVC end caps and polyester media handle temperatures up to 140°F, suitable for well water, pool, spa, and light industrial use
Harmsco HB-20-0.35W Technical Details
| Model Number | HB-20-0.35W |
| Dimensions | 20" L x 4.5" OD x 1.06" ID |
| Micron Rating | 0.35 micron |
| Media Type | Polyester-Plus pleated |
| End Cap Material | Plastisol (pliable PVC) |
| Flow Rate | Up to 30 GPM (housing dependent) |
| Max Temperature | 140°F (60°C) |
| Applications | Potable water, well water, pool/spa, light industrial |
Fits Standard 20" Big Blue Housings
The Harmsco HB-20-0.35W fits any standard 20-inch Big Blue filter housing with 4.5" diameter capacity and 1-inch center tube. Compatible with whole-house systems, well water pre-filtration setups, and dedicated sediment housings from Harmsco, Pentek, Hydronix, and other manufacturers using the 20" x 4.5" standard.
Cleaning & Replacement Schedule
Inspect & Clean
Check differential pressure. Backwash or rinse cartridge when flow rate drops or pressure increases 8-10 PSI above baseline
Evaluate Condition
Inspect pleats for damage or permanent staining. Replace if cleaning no longer restores flow or if media shows tears or degradation
Replace Cartridge
Even with regular cleaning, replace the HB-20-0.35W annually or when cleaning cycles shorten significantly
Harmsco Quality
Manufactured by Harmsco, a trusted name in commercial and residential filtration since 1946
Lower Operating Costs
Reusable design reduces filter replacement frequency and waste compared to disposable cartridges
Easy Installation
Drop-in replacement for standard 20" Big Blue cartridges with no modifications required
