Sand filters are by far the most common filtration system that pool owners use today. Sand filters use a special type of sand to coarse through your pool water, which can filter up to a range of 20 to 100 microns. Sand filters will either come with a top mount or side mount multi-port valve, which allows you to operate your filter a number of different ways. With sand filters, all of the action is isolated inside the tank, so you need not worry about manually cleaning your filter, and you only have to replace your sand about once every 3 to 5 years.