Directions for a cartridge or Diatomaceous Earth filter grid Remove cartridge elements or D.E grids from filter tank and hose off loose material. Ina pail, bucket or trash container with 5 to 10 gallons of water, add 1 liter bottle of Filter Perfect. Place cartridge elements or D.E grids in solution and soak for a minimum of 6 hours, preferably overnight. Remove from solution and rinse thoroughly. Clean cartridge elements should be allowed to dry before reinstalling.