Pool Filters 101
The two most important areas to monitor and control in your pool are filtration and proper water balance. Knowing what works is important as it can save you time and money down the road. In this section, we explain the important role pool filters play in keeping your pool healthy and clear.
There are three basic types of filtration systems. They are:
- The Sand Filter
- The Cartridge Filter
- The Diatomaceous Earth or DE Filter
Each of these filters do the same thing - they filter the water of your pool. It is the varying degrees of effectiveness that each type offers that is critical. A sand filter is simply a filter that uses a specially graded sand as the medium. Water enters the filter through the diffuser, and contaminants and debris is trapped in the grains of sand in the filter housing. The pool water continues to flow through the filter, enters laterals in the base of the filter, and is returned to the pool. This type of filter will only trap contaminants that are 40 microns or larger in size.
The cartridge filter uses a paper-like cartridge as the filter medium. This type of filter presents from 300-500 square feet of medium to filter the pool water, allowing for cleaning and replacement only once or twice per year. This makes for a real plus in the maintenance department. This type of filter is considered to produce about the same water quality as a sand filter.
The third type of filter, the diatomaceous earth, or DE filter, uses diatomaceous earth as filtration medium. This substance is nothing more than sedimentary rock, which has as one of its components silicate, which is a very good filtering medium. Grids in the filter housing are coated with DE, and can filter out particles as small as 5 microns. This filter is backwashed for cleaning purposes, and then recharged with more DE powder. A slurry of DE is poured into the pool skimmer, which then recoats the grids in the filter housing through circulation of water in the pool. Because of their high filtration capabilities, DE filters will run at a higher pressure than a standard cartridge or sand filter, which can lead to inefficiency and flow loss in the pool.