Quote Originally Posted by duraleigh
Very interesting. What are your thoughts are on why it was compacted?

It seems to me regular backwashing should prevent that. Do you think the "grey junk" could have been from not backwashing frequently enough? Have you owned the filter since it was new?
But it doesn't always. That's why I say that a filter should be broken down yearly and inspected!
Oops, just reread your first post. I wonder if the old owner thought backwashing was something he and the wife did in the shower?
A lot of things can cause the sand to gunk up and channel...high calcium levels, large organic load, adding DE to the filter, etc. Backwashing won't remove all of that.

I've tried to make this point before and got blasted for it.