The purpose of this unit is to pickup all types of fine sediment from your pool. It should have water running through it for six to eight hours every day. Filters can only take so much flow, so it's important your flow rate matches that of your pump to ensure it lasts as long as possible.
There are two types, Media Filters and Cartridge Filters. They will vary in size depending on the pool volume. They will also vary in how fine the particles that they collect will be (1 micron = 0.001mm):
- Glass Media Filter (5 microns)
- Sand Media Filter (20 microns)
- D.E Media Filter (5 microns)
- Cartridge Filter (10 microns)
Media filter use either glass or sand to hold particles inside the tank. You use a mixture of coarse and fine media to provide adequate flow whilst it picks up fine debris of all sizes. Historically, only sand filters were installed, however in the past decade, glass media has become increasing popular for a number of reasons:
- Glass will filter down to 5 microns, whereas sand will only collect debris larger than 20 microns.
- Glass media lasts twelve years on average compared with the five you expect from sand media.
- Glass needs to be backwashed for a shorter period of time, saving you water.
- Sand is however, relatively cheaper to purchase.
There are also D.E (diatomaceous earth) filters, which are even older than sand. They are barely used due to the significant difference in cost. Not only is the media per kg more expensive, but it needs to be changed every two to three months. This is not ideal since the fine powder (5 micron) will harm your lungs if inhaled, requiring protective equipment to changeover.
Cartridge filters use synthetic fabrics that are attached to a plastic frame or core, known as the element. This needs to be regularly taken out and hosed down, also requiring replacement every two years ($150 - $300). They will collect particles larger than 10 microns.
