Long story short. Well ran dry in 2010, had it drilled deeper and new pump installed. Now I think that the pump is too big and cycles too often meaning a short lifetime so I am considering adding a CSV valve. The well is 360' deep with the water table at approx 150' deep. The new pump is a Grundfos 25-S-30 and feeds a Well-X-Trol 119 Gal Tank that is 4 years old. My biggest concern with the CSV is the back-pressure. How can I check or know whether it will be ok?