That PVC ball valve is meant to be glued to something. If you want a detachable piece, you should permanently add an adapter.
My pool was threaded already with 1.5" NTP, so I added this Camlock adapter, and then snap this hose on when I need to do a backwash.
If yourYour ball valve is 1.5"2" PVC (I can't tell from the picture), thenso you could glue on this PVC adapterthis PVC adapter, thread in the Camlock adapterthis Camlock adapter, and then only connect the hosethis hose when you need to backwash.