Ok. I had a moment of self confidence and decided to saw some pipe and glue on some unions.
Did the deep clean and the water coming out was the muddy color I had been expecting from my backwashes all along. Bottom half of the sand in half the diameter of the filter seemed quite hard (maybe I was just imagining things). I popped the MPV back on with the water from the deep clean still looking nasty. Started the pump on backwash and lo and behold I have dirty backwash water. Maybe the deep clean loosened up some channeling???
Did the deep clean and the water coming out was the muddy color I had been expecting from my backwashes all along. Bottom half of the sand in half the diameter of the filter seemed quite hard (maybe I was just imagining things). I popped the MPV back on with the water from the deep clean still looking nasty. Started the pump on backwash and lo and behold I have dirty backwash water. Maybe the deep clean loosened up some channeling???