Definitely keep an eye on the PSI in the tank. High pressure can collapse the DE grids. While I haven't read or performed a study on what pressure is too high, I have replaced many grids from running at pressures under 40psi, especially older grids. So if you're non-friction (before you add any new DE to fully cleaned grids) starts high, check for blockages in the return system, or the filter. It's good to know what your free flowing system pressure is as a baseline, with new DE, and at full.
is there much of a output change if you bypass the filter "spa mode"? If not, there's definitely something blocking the line. If the output as felt by the jets jumps way up, I suggest disassembling, cleaning and reassembling the grids. A simple mistake in reassembly can be the culprit and the time and DE $$$ are far less the replacing a single grid.
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