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Sand Filter Operation

How Does A sand Filter Work ?

A sand filter as the name suggests is not always filled with sand, sand is termed as media and there are a number of different types of media though sand is certainly the most common.
The sand is a silica sand and is of a particular grade in terms of size so as to allow adequate filtration.
The water is forced through the sand when the multiport valve is set to "filter" allowing the sand to trap the small debris.
The sand when viewed under a microscope is very irregular in shape and it is the gaps between that do the filtering.
Over a period of time the sand wears out and need changing, they would be little to no difference in the physical appearance of old and new sand to the naked eye but all of the irregularities will have worn off leaving the sand as round particles and not able to filter out debris well enough.
It will also have a tendency to matt together.
Despite popular belief, it is the amount of time that water has been running through the sand that has the most influence on it wearing out, not so much the amount of debris it has colleced over time.
We suggest that filter sand is changed on a five yearly basis.