Sand Filters are the most popular filters used in swimming pool filtration. They use a specifically graded #20 silica sand to trap particles (down to 20-100 microns) as the water runs through the filter. These particles build up in the sand and eventually have to be “backwashed”. Backwashing is the process of running water through the filter backwards clearing out all of the filtrated particles through an line that leaves the filter and pool. This usually involves turning or pulling on a filter valve.
Diatomaceous Earth or D.E. Filters are the European Sports Car of swimming pool filters. They are by far the best filtration system, trapping particles down to an amazing 1-5 microns. They are the preferred filter for swimming pool techs everywhere because of the way they make the water crystal clear compared to the other types of pool filters. They use D.E. powder and their filter grids to filtrate the water. They require backwashing similar to a sand filter, except they also need the D.E. replaced after backwashing occurs, as it is flushed out with the trapped particles. This is an added step and cost associated with these filters.
Cartridge filters, in our opinion, are the best of both worlds. They not only are inexpensive, they are very easy to maintain. They use a cartridge element that traps particles down to 10-20 microns as water flows through it. They do not require backwashing, but instead require the cartridge to be cleaned via a water hose. This takes a little bit of work compared to backwashing, but can be done in under 10 minutes, especially with the use of filter cleaning aids such as the Filter Flosser.