Sand Filters
Sand Filters can filter particles from 40 to 100 microns, and are sufficient to trap most large debris in your pool's water. These filters contain between 150 - 700 pounds of special filter sand, and must be backwashed when the pressure is above the desired range. The sand in your filter can become contaminated over time by algae, debris from trees, animal hair, etc., and should be replaced every 5 - 7 years. As the integrity of the sand deteriorates, its ability to filter becomes greatly reduced and the sand bed may become "channeled" or "calcified" from hard water deposits. Gradual loss of efficiency may be hard to notice. If you are unable to keep your pool clear, even with a proper chemical balance, your sand should be changed.
Cartridge Filters
Cartridge Filters have the second-best filtration on the market. At a still-strong 15-micron size, they do a substantially good job of filtering out the unhealthy stuff that can land in your backyard oasis. Cartridges are a really good, set it and forget it (for six months) filter. There is no back-washing necessary. However, they do require a filter cleaning every six months. This is the highest-rated filter for teamwork with variable speed pumps due to the massive amount of square footage the filtration area has. They can go up to as large as 700 square feet in residential equipment.
Diatomaceous Earth (DE)
D.E. Filters are the absolute best when it comes to water quality. They filter out 1 micron in size, which means any bacteria 30 times smaller than the width of a single hair CANNOT pass through your pool filter! Pretty amazing huh? There is quite a bit of work that comes with this great filter though. The maximum square footage of surface area water that can pass through it is 72 square feet of internal surface area. That means the flow will and can be restricted when the filter is dirty. The benefits are that all you have to do is backwash once a month, and then clean out the filter once every six months. But remember, this type of pool filter needs to be “charged” with Diatomaceous Earth Powder.