Just installed all brand new 7 full and 1 half DE grids. They replace the original grids that were 7 years old. Several had broken tips that went in to the manifold, and, one or two had damaged plastic grids. But, the PSI starting pressure is the exact same, about 9 PSI, as the old! Years ago, when my DE filter was new, my starting PSI was barely above 0, about 1 PSI. I was expected brand new grids to drop me back close to 1 PSI for starting pressure.
I don't seem to have a blockage or a leak. Anybody have any ideas?