Hi. I'm Smitty. I am a professional appliance repair consultant here to help you diagnose, and repair, your appliance.
Did you have this problem before you replaced the grids and filter screen? If you did it is probably just residual DE that is still in the system. It can take a long time to get it all out believe me. A filter on a motel pool I maintained blew out once. It took me 3 months to get it to stop leaving DE on the bottom of the pool.
Other than that there is a possibility that the DE is actually sand from a busted underground pipe (not likely but I have seen it), or the filter has a hole/leak in the screens.
Please let me know if you have any other immediate concerns.If not please select a positive rating at this time. Doing so will not close your question, and after you rate my service you may ask any followup questions you like. All at no additional charge.Thank you for the opportunity to serve you. Best, Smitty**How to rate your expert**