Pool filters

A filter is vital to the cleanliness of any swimming pool. It removes dirt and debris, re-circulates clean water, and distributes important pool cleansing chemicals evenly throughout the pool. Filters and pumps work hand in hand and some are combined units.

Types of swimming pool filter

There are three different types of swimming pool filter, the sand filter, the diatomaceous earth filter, and the cartridge filter.

All three types of filter have different characteristics and different experts have different views on which one is the best. What most people do however agree on is that filter size is more important than filter type. All things being equal, you should always buy the biggest filter that your budget can run to and should always opt for a filter that is larger than your pool requires.

Sand filters

A sand filter uses sand within a specific grade range to trap small particles of dirt. But because the sand particles are comparatively large, there effectiveness at collecting dirt actually increases as they trap more and more unwanted material.

A sand filter can last for up to 10 years before it becomes necessary to replace the sand bed, but these filters do require periodic backwashing to ensure that the sand bed does not become clogged up with the extricated waste. Sand filters do become less effective over time as the sand particles lose their sharpness and characteristic problems like channelling start to develop in the sand bed. Replacing the sand bed does of course renew the filters performance.

Diatomaceous earth filters (DE)

Diatomaceous earth filters are generally regarded as the best pool filters available today, mainly because they can collect dirt that has a particle size of 3 to 5 microns. This is smaller than that capable of being collected by both sand and cartridge filters.

Diatomaceous earth filters work by using a special powder called Diatomaceous earth powder (DE powder).

Like sand filters, diatomaceous earth filters need backwashing (multiple times for a single cleaning), but they also require the addition of DE filter powder which is done by adding the powder via the skimmer. The need for backwashing is indicated when the pressure reading exceeds a certain level (as with sand filters).

It is also necessary to overhaul DE filters annually and add DE powder to the filter grids.

Cartridge filters

As their name suggest, cartridge filters have a removable filter that can be taken out and cleaned or replaced.

These removable cartridges can last up to 5 years and can be cleaned periodically by using a pressure hose, or any other device that can be used to direct a jet of water at them. The drawback to a cartridge filter is that is in unable to remove many of the smaller dirt particles that the other two filter types can extract.

Cartridge filters have a lower performance than both sand and diatomaceous earth filters, but they are popular with owners of above-ground pools because of their price, ease of cleaning and limited level of ongoing care.

Backwashing

Backwashing is a term used to refer to the cleaning of a filter by reversing a pool pump flow valve so that the water passes back through the filter (in the wrong direction) and flushes out the accumulated dirt. It is a simple and easy to perform process.