Your sand filter dial head has the following positions. They are filter, backwash, rinse, winterize, whirlpool, and waste or drain.
Filter position: Used when you are running your pool and you want your pool water to be filtered. (most common position)
Backwash position: Used only when your filter is dirty and you want to clean the sand in your filter. Water is reversed through the sand and lifts out all the dirt and then discharges it out the waste pipe.
Rinse Position: Used only after backwashing. Does same thing as the “filter” position only water goes out waste pipe instead of back into pool.
Winterize position: Used in winter to relieve pressure off seals so they don’t flatten and leak over time. Also lets air into the filter to help with draining the water out of your filter during winterizing.
Whirlpool position: Used when you want the water to bypass you filter. Handy when diagnosing problems with too much pressure or checking how dirty your sand is.
Drain position: Water from pool does not get filtered but goes directly out your backwash waste hose. This position is also handy if you are vacuuming up debris that you don’t want in your pool or filter.