At what pressure should you backwash a sand filter
The back pressure at which it's time to backwash a sand filter is about 6-8 psi above the baseline pressure of a clean filter. Just after following the procedure to backwash and rinse your filter, check the sand filter's back pressure at the time you return the pump and filter system back into filter mode. This is the baseline pressure of your clean filter. As the filter gathers particulates from the pool water, the back pressure will rise over time, as indicated on your pressure gauge. Once the pressure reaches 6-8 psi above the baseline, it's time to backwash.
Some advice: Don't assume the baseline pressure will remain the same for your sand filter. The baseline pressure will change over time and when the sand media is replaced. Typicallly baseline pressure will go up slightly over a season due to captured particles that are difficult to backwash out. Use of a filter cleaner will help remove these captured particles.
More advice: Even with the use of filter cleaners and proper backwashing, sand media will not last forever. The constant water flow and movement of particles in the sand over time shears the surface of each little sand grain. Like a river flowing over rocks, over time each sand grain surface is smoothed, and thus its effectiveness for capturing small particles is reduced with ongoing use. A typical rule of thumb is to replace the sand media +/- 5 years. Some pool owners do it more often, some less. It depends on how long your pool season is each year and how much debris the filter much extract from the pool water.
Jul 16, 2014 |
Hayward SAND FILTER, PRO SERIES