I don"t know where you live at But here in Mercer county Pa. If you have that trouble with Low water flow and small sand You better be calling the driller that drilled it. Do you know how much water the well will make without over pumping it? Do you know the recovery rate? Is it a rock well or gravel well? Is there a flow reducer on the well? These are some of the things you need to know before you "Blow the well out" Or you could very well Blow the well out at least the bottom of it. We have wells here that are finish in sand and gravel That We stomp Stones and rock down on the bottom to keep them from "Blowing out" Pushing sand 20 or30 feet right up the hole and shutting off the water. Good luck.