If you put a little salt or vinegar in the water, the shellfish's stomach will be stimulated and spit sand violently. In addition, you can also put a knife or a piece of iron in the water where shellfish are put, which will also speed up the speed of shellfish spitting sand. In order to prevent shellfish from sucking back the sand spit out by shellfish, you can put the quilt in the filter basket when soaking, and then put the filter basket on the basin, so as to keep the distance between the filter basket four or five centimeters. In this way, the sand spit out by shellfish will sink to the bottom of the basin and will not be sucked back by shellfish.