One more thing:
I'm doing some reading on the net about the DE filters and one point has come up a couple times that caught my eye. That's that the amount of DE recommended by the manufacturer (in this case Hayward) is way too much for what's needed. Hayward calls for 5lbs., IIRC. I have a tub that once held 7 lbs of Cl pucks. I know that if I fill it roughly 4/5 of the way with DE (not packed down) and dump it in the skimmer when I start the pump, everything seems to work nicely and my water is absolutely clear throughout the season. (I also use the Hayward wand to really clean out the filter tank when I backwash).

I don't know how much DE that really is, but it works for me, and I back washed twice last summer, after getting the intial gunk out. I bring this up again because I'm starting to think seriously that you need to cut back on the DE.