my clean pressure on my DE filter is 20 psi. When I turn it to spa mode it jumps to 27 psi and the spa gets cloudy and murky. It seems DE is getting back into the spa. I have no idea how old the grids are (they could be up to 9 years old) and when I cleaned them a couple weeks ago I didn't notice any tears but there must be. I can't think of any other reason why it would be doing that. Time to replace them?