Swimming Pool Filters

An important aspect of swimming pool maintenance is proper filtration.  There are three basic types of filtration systems, and a pool can be properly maintained using any of the three. Following is a brief description of each type of pool filter:

The sand filter
This type of pool filter uses a specially graded sand to trap particles about 20 microns or larger in size. Water is pushed through the sand filter, trapping contaminants and in the grains of sand in the filter housing. The pool water flows through the filter, leaving the contaminants behind in the sand, and then enters a set of lateral tubes in the base of the filter, and is returned to the pool. As a sand filter traps more debris, it becomes more efficient, trapping more debris.  Eventually, however, as it becomes clogged with too much debris, the pressure on the filter increases, and the flow of the water drops.  This is when you need to clean your sand filter by “backwashing” it, rinsing to repack the sand, and placing it back onto the filter.  This should be done once every couple of weeks or more – depending on how quickly your filter needs to collect debris.  The sand can be replaced easily and with little cost if it ever becomes too dirty.  Typically, a sand bed should be replaced every seven years.  If you use your pool year-round, however, you may need to replace it more often.

The cartridge filter
This type of pool filter uses a paper-like cartridge to trap particles about 20 microns or larger (similar to the sand filter’s cleaning performance). Basically, water passes through the filter, and the filter captures contaminants.  Cartridge filters have a greater area than some pool filters (between 100-500 square feet), so they clog up less frequently, making it necessary to clean only once or twice per year.  Cartridge filters can be cleaned easily, just by hosing them off.  Every time you clean your filter, the filtering ability decreases.  You should replace your cartridge every two to five years.  If you use your pool year-round, or your pool is located in a place that creates more debris and algae however, you may need to replace it more often than someone who uses his pool seasonally.
 
The diatomaceous earth or DE filter
This type of pool filter uses diatomaceous earth (fossilized, microscopic exoskeletons of sub-aquatic creatures called  Diatoms) to trap particles as small as 3 microns – smaller than what the naked eye can see!  The filter area of a DE filter is commonly around 60 and 70 square feet.  Grids in the filter housing are coated with the DE filter powder.  When it needs to be cleaned, the filter is backwashed and then refilled with more DE filter powder by pouring the DE filter powder into the skimmer and recoating the grids.  It is the powder itself that filters contaminants out of your pool water.  Once a year, you should give your DE filter a thorough cleaning