Pool Sand Filter Systems

Sand Filter Systems for Pools

A pool filter is essential for keeping the water in a pool safe to swim in. Sand filters are an effective and popular cleaning option for both in-ground and above-ground pools.

A sand pool filter uses a pump to force pool water through a tank of specially selected sand, which filters out dirt and debris down to sizes of around 20 microns across. Compared to cartridge filters, their main alternative, sand filters are cheaper and simpler to operate. On the other hand, they also need to be backwashed every few weeks in order to remove the accumulated debris from the sand.

The bigger the pool, the more powerful the pump in its filtration system has to be. Pool pumps are typically rated in terms of litres per minute. The more water in the pool, the higher a flow rate is needed to recirculate it in a given amount of time. For hygiene purposes, experts recommend using a pool pump that can recirculate the full volume of a pool in eight to twelve hours. An undersized pool pump will not clean your pool effectively while an oversized pump will waste electricity.

Like any pool filter, sand filters come in different sizes. There are two numbers to look at. The first is the size of pool that a filter is rated for. The second is the amount of water that can pass through it each minute. The filter’s maximum flow rate must be higher than the flow rate produced by the pool pump. An undersized filter leads to less efficient cleaning and the pressure buildup can serious damage both the filter and the pump. On the other hand, there is little downside to using filter with a maximum flow rate much higher than the pump, particularly as the filter flow rate will decline over time between cleanings.

Over time, the dirt trapped by sand filters starts to clog them up, making it less efficient at filtering. The pressure valve on the filter will show higher than normal readings as this happens. Typically backwashing should take place about once a week. Water is lost each time the filter is backwashed, so excessive backwashing will waste water and pool chemicals. The sand in a pool filter will also need replacing around every five years, as it wears down over time and becomes less able to trap dirt. This should be sand specifically selected for pool filters, as other types of sand may not be coarse enough for effective dirt filtration. Some alternatives to sand are available, such as recycled glass.