Normally, for a DE filter, rinsing the grids/fingers off with water is sufficient. If there is stuff that won't come off with just water you can soak them in detergent. Ideally, for that, you want to use TSP (trisodium phosphate), but that is often difficult to find. The best alternative is automatic dish washer detergent. Typically you use one cup of TSP/detergent in a garbage pail of water and allow to soak overnight, then rinse off.