We replaced both our pump and filter system last year so everything is brand new but we still have DE blowing into the pool. We do have a small leak from the pump to the filter system but the DE is not blowing back thru the skimmer but out the return port. Our DE is old. Could this be an issue of it not coating the filter properly?
I haven’t heard of old DE powder being an issue. The more likely cause is a hole in one or more of the grids, a crack in the manifold, a bad standpipe o-ring, or a bad spider gasket in the multiport valve.