The Importance and Function of the Filter
To prepare you to choose the perfect filter, let's start with explaining the job of the filter in your pool. The filter and pump are the heart and lungs of the pool circulation and filtration system. The primary purpose of the filter is to keep your pool clean by removing undissolved debris from the pool water.
How the Filter Works
Pool water comes from the circulation pump into the filter where small debris particles are removed through depth or surface filtration, and then goes on to the heater or back to the pool.
A filter works through mechanical separation of water and debris through surface or depth filtration. Sand filters use special filter sand, cartridge filters pass water through a fibrous element, and DE filters pass water through a thin layer of diatomaceous earth that is coated onto a grid.
A gauge located on the filter or valve can be used to measure the back pressure or resistance in your filter system. When the pressure increases by 10 psi, the filter should be cleaned to reduce resistance and improve water flow.
Cartridge filters require disassembly and cleaning of the cartridge periodically to remove debris from the filter.
DE and Sand filters require periodic backwashing to remove debris from the filter. To accomplish this water is directed through the pool filter by a valve (multiport, vertical, or other). Once the water runs through the filter, it flows to the pool heater or back into the pool. To backwash, the valve is manipulated to reverse flow and direct debris-filled water to waste.