Do I "have" to soak my filter grids/cartridge after I hose the cellulose/DE off of them. They certainly aren't bright white anymore, but they have only a faint brown discoloration. This is my second year with the filter, and I haven't soaked them yet. Is that bit of dirt really interfering with anything? I imagine the second i reinstall them, and coat them with the cellulose they will get dirty almost immediately.