I just noticed that Pool School recommends running the backwash cycle twice for more effective cleaning, the other day.
What it says....
Sand filters will have either a push/pull main valve or a multiple position valve (multiport) for cleaning the debris trapped by the sand. Whenever changing the position on the main valve, you MUST have the pump off or you will break something. First make sure that any valve on the discharge/waste line is open and any discharge hose is attached and rolled out to where you want the dirty water to go. After turning off the pump, move the lever to the "BACKWASH" position and restart the pump. Most multis have a view glass so that you can see the debris coming out of the filter, other filters will have a section of transparent pipe on the backwash line. The water will run clear for a moment, then get dirty, and finally run clear again. When the water in the glass is ~ clear, turn off the pump. If you have a multiport valve with a "RINSE" setting, switch the multiport to "RINSE", otherwise switch to "FILTER", and run the pump for about 15 seconds. Repeat the backwash cycle. Finally, reposition the valve back to the normal "FILTER" position, and you're all set until the unit needs to be cleaned again. Please note that this process removes water from the pool, so be sure to keep an eye on the water level and don't start the cleaning process if the water is already low! For more detailed information on cleaning Sand filters, see this post.