Pool Filter Basics


Of the three basic types of pool filters, all in widespread use – Sand, DE (diatomaceous earth) and Cartridge, which filtration type is best?

All three filter types are used in series with your main pool pump, allowing the water to pass through the filter media before re-entering the pool. The media traps dust, dirt, oils, hair, and other small particles and removes them from water. Each filter type has its pros and cons, but when used properly, any of the three will do an adequate job of keeping your pool clear and free of all but the smallest particles. However, Bogner Pools does have a preference, and we’ll explain why below.

The three common choices:

Sand Filters

  • Filters particles down to 30 microns which is the least efficient of all three

  • Simple to backwash but needs it often

  • Uses a substantial amount of water to backwash

  • Deep clean filter once a year

DE Filters (diatomaceous earth)

  • Filters particles down to 3 microns, which is the absolute best of all three

  • Requires recharging the filter with DE which is a small expense, but saves water

  • Requires some disassembly, which takes a little extra time

Cartridge Filters

  • Filters particles down to 10 microns, not the best or the worst

  • No backwashing required so it saves water

  • Must tear down filter to clean grids each time, grids can be a chore to get clean

  • Grids need replacing often so this becomes expensive in the end

Some argue that sand is the easiest to maintain but we know its filtering ability is the lowest – down to about 30 microns. This can be particularly noticeable if your pool is lighted at night. Cleaning a sand filter is easy, but the constant backwashing will tend to throw your water balance off with the introduction of so much new water all the time. Sand does occasionally need a more thorough cleaning than backwashing alone can do. Once a year deep cleanings are required to break up any scale formed on the sand.

The most effective filter media, is DE (diatomaceous earth). DE is made up of fossilized diatoms (porous, sponge like microscopic organism) and can filter down into the 3-5 micron range. The difference in water clarity will be obvious with DE. DE filters can be backwashed but some townships require a DE separation tank for back-washing DE filters. Bogner Pools recommends a full cleaning and inspection of the filter every 90 days. This saves water and insures 100% new filter media to keep your water crystal clear.

Cartridge filters require no backwashing involved so your water balance tends to stay put but the filtering ability just doesn’t match a DE filter. Cartridges do wear out and need to be replaced every few years or more. Some municipalities have outlawed sand and DE filters so in those areas, cartridges may be the only choice. Proper cleaning is the same time and energy as a full cleaning on a DE filter.

After 60 years in business, can you tell which filter we recommend? Bogner pools has sought to educate our customers about water quality to help create a healthy environment for thousands of families in the Inland Empire. Bogner Pools is ready and willing to discuss the filtration needs for your swimming pool project.

-Rick Nelson
Design and Sales Consultant
Degree in Chemistry