There are three popular types of pool water filters – Sand, Cartridge, and Diatomaceous Earth (D.E).
In this method, impurities are extracted from the water using sand to attract and collect debris. Sand filters must be back-washed (running it in reverse) to clean out the collected waste. Sand filters are economical, relatively low-maintenance, and easy to use. Of the 3 types of filters, sand filters will take the longest to clean a dirty pool.
The cleaning element in this type of filter is made of a thick, dense, fabric-like material, which has a larger surface area than sand filters and captures smaller particles. Cartridge filters hold more dirt and debris before cleaning and can capture smaller particles faster.
Diatomaceous earth (DE) Filters
Diatomaceous earth is a naturally occurring powder made up of the remains of microscopic organisms called diatoms. Particles of DE are as tiny as 1 micron. This method of filtration captures the smallest particles, trapping debris as small as 1-5 microns. Once the pressure rises, the filter is back-washed just like a sand filter and then "recharged" with more DE powder.