I am not sure there is a right answer to this but I am interested in other thoughts.
I usually would backwash and re-load DE just before closing but I notice that I lose some DE when draining the filter. So I am thinking maybe I will just wait until spring to backwash and reload the fresh DE at that time. I know this may go against some people's sensibilities to leave a filter dirty all winter but other than that is there any good reason to backwash before winter? Thanks.