The Harmsco HB-20-0.35W Calypso Blue cartridge has a 0.35 micron absolute rating, making it one of the finest pleated polyester filters in the Harmsco line. This ultra-fine filtration is ideal for cyst reduction (Cryptosporidium and Giardia), fine sediment, silt, and turbidity removal, delivering high-efficiency filtration for whole-house, commercial, and municipal water applications.

The Harmsco HB-20-0.35W measures 20 inches in length by 4.5 inches in diameter (Big Blue size) and is designed to fit Harmsco Calypso Blue housings as well as standard 20" x 4.5" Big Blue housings. It provides approximately 150 square feet of pleated polyester media surface area and supports flow rates up to 20 GPM, making it suitable for high-demand residential and light commercial systems.

Replacement intervals for the Harmsco HB-20-0.35W depend on water quality and usage, but typically the cartridge should be replaced every 6 to 12 months, or sooner if you notice a pressure drop of 15–20 PSI across the housing. The reusable, rinsable pleated polyester media allows for cleaning and extended service life compared to standard spun or melt-blown cartridges, making it a cost-effective long-term solution.

The Harmsco HB-20-0.35W Calypso Blue cartridge is manufactured from FDA-compliant materials and is tested to NSF/ANSI Standard 42 for material safety. At its 0.35 micron absolute rating, it effectively reduces fine sediment, sand, silt, rust particles, turbidity, and waterborne cysts such as Cryptosporidium and Giardia, improving water clarity and protecting downstream equipment and UV systems.

Yes, one of the key advantages of the Harmsco HB-20-0.35W is its rinsable pleated polyester construction. Unlike disposable spun cartridges, this filter can be removed, rinsed with clean water to dislodge trapped sediment, and reinstalled — extending its usable life significantly. Once the cartridge can no longer be cleaned effectively or pressure drop remains high after rinsing, it should be replaced to maintain optimal 0.35 micron performance.