A sand filter is a device that uses sands as a natural filtration substance to clean water. Just like water in underground aquifers is made pure by going through various layers of sand and porous rock, a sand filter seeks to take nature's own design and use it as well. Unlike other types of filters, sand filters can be very environmentally friendly products often used in swimming pools and even commercial wastewater applications.
Those considering a pool sand filter should know that there are some very simple pool maintenance steps needing to be followed that will help maintain good water filtration. The most frequent task needing to be done is to clean the pool filter, usually approximately one time per month. This is done by backwashing, or reversing the water flow through the filter and then discarding that water.
In some cases, it is recommended to change the sand filter so that it maintains a certain level of efficiency. Many pool maintenance experts and shops recommend changing the sand in a filter once every five to seven years. The sand is sized and shaped in a way that prevents very small particles, often only the size 20 microns, from passing through. Over time, the sand loses its rough edges and is less effective. Thus, the system has to spend more time running in order to filter as well as it did when the sand was new. This can shorten the life of the sand filter.
A sand filter is one of the most common types of filters used for swimming pools. For a residential pool, they usually start at approximately $400 US Dollars (USD). However, the cost is often dependent on the size of filter needed and perhaps the brand chosen. However, for larger pools and aquatic parks, a sand filter can take up a substantial amount of space and multiple thousands of dollars. The benefit of a sand filter is it is usually able to last multiple decades as long as it is not abused and well maintained throughout the years.
Sand filters can also be used in other types of applications, including commercial water purification systems for drinking and wastewater. In these situations, a biofilm forms on top of the sand. It has a consistency similar to gelatin. The biological elements help digest and remove harmful bacteria. Once this is complete, the water filtering through may be nearly completely free of bacteria.