Just a comment Rbrenton. I have a DE filter also and so far I haven't had to deal with this problem at all (knock on wood).

I'm not sure how old mine is as it came with my house, which I purchased 1 and a 1/2 years go, but it looks fairly old.

So, it may be that this is not a common problem with DE filters and that yours is just due for a replacement. Not sure.

I may one day switch mine for a sand also, but mainly because I never know what the heck to do with the DE when I drain the thing.