Pentair Pentek WS-20BB, 20" Big Blue Water Softener Cartridge, 20" x 4.5"

REDUCES HARD WATER SCALE - Sodium-form cation resin with 4,500-grain capacity (as CaCO3) reduces calcium and magnesium that cause scale buildup in pipes, fixtures, and appliances | FITS STANDARD BIG BLUE HOUSINGS - Designed for 20" x 4.5" Big Blue filter housings; drop-in replacement with no modifications or adapters required for quick cartridge changes | BUILT-IN RESIN PROTECTION - Polypropylene pre-filter and post-filter contain the 20 x 40 mesh resin media, preventing resin migration and ensuring cleaner, consistent water output | RELIABLE CONSTRUCTION - Polypropylene endcaps and Buna-N gaskets provide a secure seal; internal expansion pad maintains cartridge integrity throughout the full service life | RECOMMENDED OPERATING CONDITIONS - Flow rate of 2.0 gpm (8.5 Lpm) for optimal contact time; operating temperature range of 40-100 degrees F (4.4-37.8 degrees C) for cold water applications