The Three Filter Types in Use Across Boston Pools
Residential pools in Greater Boston are equipped with one of three filtration technologies: sand filters, cartridge filters, or diatomaceous earth (DE) filters. Each operates on different principles, requires different maintenance procedures, and has different failure modes. Understanding which type you have is the starting point for any filter service conversation.
Sand filters pass pool water through a bed of #20 silica sand or alternative media such as ZeoSand or glass media. Particles are trapped in the sand bed and flushed out during backwash cycles. They are the most common filter type in older New England installations due to their low maintenance requirements and durability. Cartridge filters use pleated polyester filter elements that trap particles as water flows through. They require periodic cleaning and eventual cartridge replacement rather than backwashing. DE filters coat a grid of filter fabric elements with diatomaceous earth powder, achieving the finest filtration of the three types — capable of capturing particles down to 3–5 microns.