Swimming pool filters are an essential component of a pools water circulatory system and help to maintain clean water for swimmers. Filters are plumbed into the plumbing network after the pool pump and before the pool heater. A pool filters main purpose is to trap dirt and debris and prevent it from entering the heating system and being circulated back into the pool. There are three main types of pool filters that we will discuss: sand filters, cartridge filters, and DE (diatomaceous earth) filters.
Sand Filters:
These are among the most common and least expensive options for pool filtration. The filter tank is filled with a specific, generally silica, pool filter sand. The tank is filled about 3/4 with sand, with the remaining 1/4 being free air space. Water is plumbed into the top of the tank and the sand is the media in which the water passes through as it makes its way out the bottom of the tank. Dirt and debris are trapped in the sand and will remain there until the system is backwashed. All pool filters should be equipped with a pressure gauge that typically runs between 10 and 25 psi. Generally, when the psi exceeds 25 or when it gets to be 10 psi higher than normal it is time to backwash your system. Most sand filters have a multiport valve that allows you to reverse the flow of the water. A hose is connected to the top of the filter and water is flushed up from the bottom. This removes the dirt and debris that has been trapped in the top of the filter. In addition to backwashing periodically, the sand in the filter typically needs to be changed every three to five years.
Cartridge Filters:
These filters are a popular option because of the minimal amount of maintenance required. Cartridge filters come in multiple varieties, generally ranging from one to four cartridge elements. Typically, these filters are made of polyester wrapped around a heavy plastic or PVC core. Water in these systems is filtered from outside the cartridge through the polyester pleats and into the core. The cartridges should be taken apart and cleaned periodically. This is an easy process and using a garden hose is typically sufficient. Cartridge filters have a long average service life and when well maintained can last 4 to 8 years.
DE (Diatomaceous Earth) Filters:
DE filters are considered to be the media that best cleans pool water. However, they also generally need the most maintenance and the fine particles can cause health problems if inhaled. DE is made up of crushed seashells and silica secretions from microscopic sea creatures. DE filters have internal grids made of a cloth mesh that is then coated with the DE powder. DE can trap smaller particles than cartridges and sand, which leads to very clean and clear pool water. DE filters, like sand filters, must be backwashed periodically. Unlike sand filters, some of the DE power leaves the tank during backwashing and more DE will need to be added after.
Ultimately the decision of choosing a pool filter is up to the pool owner. Factors such as efficiency, maintenance, and cost should all be considered. Qualified pool equipment companies can make recommendations based on the desires of the client.