I have a Pentair FN60 DE filter and noticed DE on the bottom of pool and in my robot cleaner. I replaced the grids (they were pretty ugly) and after putting all back together and running about a week now I still get DE settled on bottom. Seems to be less but still coming out. I took it apart today and checked if grids in ok. They looked seated. Took apart and filled manifold with water to check for leaks and noticed one spot that is slowly dripping water. Would this be my culprit or could it be the o-ring on the return tube? It really doesn't seem like a very good seal at the top of the grid to the manifold to begin with. And what the heck is that plastic plate for on top of the grids? It doesn't seem to do anything at all. Maybe I'm missing something please help!!!!