The Filter
The filter helps to keep your pool’s water fresh and clean by removing oils, grease and dirt from the water. There are three basic types of pool filters: Sand, D.E. (Diatomaceous Earth), and Cartridge. All filters work by the same general concept – water is passed through a media (sand, D.E. or cartridge), which catches microscopic particles, blocking them from entering back into the pool. Since the filter is the last line of defense in trapping debris, it is important to use the proper type of filter and clean it as necessary. Generally, when the pressure gauge on the filter increases 10psi above its normal operating level, it’s usually a good time to clean your filter. For specific instructions on operating and maintaining your filter, refer to its operating manual or your local pool professional.

Sand Filters
Because if its simplicity of operation and maintenance, the high-rate sand filter is the most popular type. Sand filters use layers of specially graded sand (#20 silica sand) to trap tiny particles (20-100 micron range). Over time, the collected dirt and debris in the sand slow down the water flow. An increase in the water pressure on your filter gauge is sign that the filter needs to be cleaned. Sand filters are cleaned by backwashing, which reverses the flow of water through the filter, lifting out the particles and pumping it out a waste line. As a sand filter collects dirt, its efficiency increases (to a point) to trap even more dirt so it’s important not to backwash your sand filter more often than necessary. Chemical filter cleaners are also used to help keep a sand filter clean.

DE Filters
The most efficient type of pool filter on the market is the DE (Diatomaceous Earth) filter. However, along with the effectiveness comes increased maintenance and complexity. A DE filter contains diatomaceous earth, a fine white powder made from the chemically inert, fossilized remains of sea organisms called diatoms. This powder, which can filter our very small particles (1 to 5 microns), is held in place by grids or “elements”. As water passes through the coated grids, particles are collected on the surface and clean water is returned to the pool. There are various methods of cleaning D.E. filters, including backwashing; in most cases the D.E. must be replaced whenever you clean the filter.

Cartridge Filters
Cartridge filters are the choice for most spas and many smaller above ground pools because they are easy to clean and have a low replacement cost. Cartridge filters use replaceable pleated filters made of polyester cloth or corrugated paper – like large oil filters – trapping particles as small as 10 microns. Instead of backwashing to clean, cartridges are removed, hosed off and soaked in a cleaning agent. Cartridges should be replaced when they show signs of wear or fail to maintain clear water in the pool. It’s also a good idea to have an extra cartridge on hand to use while the other is being cleaned.

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