Above ground pool filters are fundamentally identical to their in-ground counterparts. They serve to remove both large and fine debris from the pool water by cycling it through a filter cartridge. The water is propelled by an electric motor turbine which is designed to last for many years. There are three distinct types of above ground pool filters available, each of which uses a different filtration method. Certain filtration methods are more effective than others, as explained below.
1. Sand Filters
Above ground pool filters which use sand have been around for a long time. However, they are still used today. These pumps work by cycling water into the top of a filter filled with silica sand. As the water passes through the sand, particles are removed. The water exits the bottom of the filter and returns to the pool . Over time, the particles build up at the entry to the sand as well as inside the sand. To continue using the filter without replacing the sand, simply reverse the water flow using the on-board reversal valve. Eventually the silica sand will need to be replaced.
2. Cartridge Filters
Cartridge filtration offers superior water cleaning when compared to a sand filter. With about double the cleaning effectiveness, buying this type of above ground pool filter can be worth the cost. It is important to note that the cartridges do not need to be replaced, only cleaned. Debris is captured on the surface of the cartridge as water passes through it. When the debris builds up, it must be removed by disengaging the cartridge and washing it off in a chemical known as TSP, followed by a spray of water. A dirty filter is neither as efficient nor effective as a clean one.
3. Diatomaceous Earth Filters
The most effective above ground pool filter available, D.E. filters screen out the smallest of particles. This material looks and feels like very fine powder and is actually composed of long dead microscopic organisms. Each microscopic particle of D.E. is porous and has tiny holes on the surface which capture pool debris. Water is allowed to pass through the holes, but particles get stuck. However, D.E. is not used alone. Users must coat a special structure within their filter with this powder. Follow the filter instructions to learn how this is done (it is called “pre coating” the filter).