The easiest way to clean your sifting litter box is to simply take out the sifting tray and empty it into a trash bag. Then, you can use a brush to clean off any remaining messes from the pan. Next, you’ll want to place the empty tray back into the litter box and pour some of your fresh litter into it. You should do this once every two days or so, depending on how many cats you have in your household.