Backwashing a filter flushes out all of the caught particles from the filter media. Filters can get clogged in a matter of just a few days if a pool has had a lot of activity. Sand filters for commercial pools must be backwashed often, at least once per week or even once per day depending on how much the pools are used.
D.E. (diatomaceous earth) filters for commercial pools should be backwashed and recharged with new D.E. powder at least once every two weeks or once a week depending on how much the pools are used.
Most pool filters will have a pressure gauge installed on the top lid that allows you to see how much pressure in pounds per square inch (psi) is inside the filter. A clean filter will usually operate between 10 – 20 psi. When the pressure reaches around 30 psi, it usually means it’s time to backwash the filter.
For sand filters, if the pool remains cloudy even after backwashing, there may be a problem with the sand inside of the filter not properly filtering the water.