My shallow well (approx 50 ft) w/jet pump (foot valve at approx 20 ft) started pumping sand through my water-to-air heat pump. I installed an in-line filter but it clogged overnight. I thought about a sand separator but that sounds like a temporary fix and it would be a real pain to put it on the suction line prior to the pump. I switched my AC water source to another driven shallow well (approx 25') but it has a lot of iron deposits and clogs the filter in about 2 days. Also, the water near the surface is not nearly as cold as my deeper well water therefore my AC is not nearly as efficient (runs 24/7). I was told that my deeper well probably has a cracked casing and is allowing sand to get to the foot valve. I replaced the foot valve about 2 years ago and while doing so I dropped a weighted string to the bottom. That's how I estimated 50 feet. I suspect the steel casing goes down 20-30 feet. Is there a way to repair a casing that has corroded through? A repair sleeve of some type? OR is my only choice a new drilled well? OR is this my problem at all?