Interesting.

I've been using a Hayward Pro Grid DE filter (60ft2), single speed 1hp pump which cycles on/off per timer settings, with my 20k gal pool since 2004 without any apparent issues. What kind of issues would one experience if the grids weren't recoating properly?

Once the pool is clean after spring startup, I may have to backwash and recharge once during the season, which runs early May to early Oct here (last season I didn't have to backwash until fall closing!).