Okay, I decided not to backwash and let it go a couple of days to see what would happen, and last night I noticed that my water was clearer than it has ever been. There was virtually no particulate matter to be seen in front of the pool light!!

I guess the DE trick does work, and perhaps I just introduced it to the filter too fast or something. At any rate, next time I backwash I'll go a little slower with the DE and see how much I'll need to get the job done.