Pool draining water....

I recently purchased a home with an inground pool, the past week we have had a lot of rain and the water level was almost to the top of the skimmer. I have a Hayward sand filter so I unrolled the backwash hose and set the filter to backwash and drained some water out. I then reset the the gauge to the filter setting and not thinking much of it I walked away. About 20 mins later I went to roll up the backwash hose and hang it up and it was still draining water out of my pool...even though the gauge was set on filter. Can someone please help me. Thank you. Brenda

You probably need to replace your spider gasket.

Welcome to the forum. That spider gasket, sometimes called a wagon wheel gasket because of its shape, is in the multiport valve. Common thing for the ribs, or spokes, to get damaged and it will fail to isolate the ports correctly. Pretty easy to replace, easier to inspect. Put the handle midway between positions to release spring tension, then remove the 6 screws that hold it together. Before you do this mark the bodies so you can orient them properly for reassembly. With the 6 screws out pull the top section off and you will see the gasket in the part that stays with the pipes. Nothing will spring apart so don't be afraid to open it up and look. Chances are the spokes are damaged or lifted out of their channels. Replacements are about $10. When you get this far repost and we'll tell you how to replace it. A big no-no is to switch valve positions while the pump is running.
Al