A lot of DE in your pool indicates your filter is malfunctioning for some reason. I would open the filter, and CLOSELY inspect all gaskets, o-rings, grids and connections. The fact that the issue started when you serviced the filter leads me to believe there is "probably" an easy fix issue. An out-of- place gasket or o-ring letting water bypass the filter or maybe a torn grid. When you cleaned the filter after the problem started, was there DE on the grids or in the bottom of the filter housing? Is your filter pressure normal? I'd bet it is running low. Do you know if your filter is a 2000-series or FNS - or something else.