During the season I'll wash out the grid a couple of times, usually after the pollen and other tree discharge is done falling, and that is just with the hose, however at the end of every season after is all shutdown I clean the grid with the hose again then put the grid back in the housing fill it with water and use the liquid grid cleaner, soak it in the housing over night and rinse the next day, flush and dry the housing and air dry the now white (like new) grid, reassemble the filter and its ready for a new season next year.
I most certianly removed the oils and greases, and yellow pollen staining. It always has great flow come spring start up.
jb :monkey: