I have a 4 in well that is 205 ft deep, water level 84 ft and pump set at 100 ft. Problem is ti is pumping sand and sediment, buillds up in 82 gallon tank and get into house. Have filter before house with back flush and washable filter. Still this does not solve problem. The casting is pvc and must not be down futher enough and pump is pulling sediment from sides. What do you suggest is problem and what is cure????? Is it possible to lower 4 in casting or go with 3in casting and 3in pump to get casting down below pump level. This is for a residental rental in south georgia. thanks, sidney