How To Clean and Acid Wash A Swimming Pool DE Filter – Part 1 and Part 2. Host Tim Casey goes into detail as to how to clean out and acid wash a D.E. (Diatomaceous Earth) Swimming Pool DE Filter. Produced by Master Image Productions For Poolandspa.TV and Poolandspa.com, this Two Part Mini-Series covers all the steps necessary to get your old, clogged DE Pool Filter into shape.