My filter seems to work OK in normal use, as I see lots of crud flushed out every time I backwash. But when I am vacuuming, I see a fine blue grey cloud of yuck coming back thru the inlets. I never saw how the pool guys loaded the filter, but I think it's just coarse sand. Should I reload my filter perodically, and if so, how?

I clean my pool filter once a month by pressure cleaning it from top to bottom, and replace the filter once a year. You should have a small pressure relief valve on top. twist to the left and wait until all air is gone. Then open the large valve which opens the top.

Depends on the filter itself, but often the valve assembly can be removed from the top. On a backyard pool you shouldn't need to do this any more often than two year intervals. Hair and oils can build up in there, and after awhile the sand can begin to solidify due to high calcium content resulting in channelling and poor filtration. If you are using a different medium than sand like zeolite, the service interval will be shorter as it doesn't let go of things in a backwash quite as well as sand.