will do, sounds like an easy test. i will compare to my gps and report back the to group. thanks! do you know if there really is a difference between the pressure switches for air and water? is it just the diaphram part,, or is there no difference.The air in the tank won't make any difference. Just turn off the pump and open the line to the upper tank. When water stops coming out at the upper tank, the pressure on the gauge at the bottom will be the exact amount needed to make up for elevation. Multiply times 2.31 if you want to know the elevation in feet. But you really only need the pressure to figure the pump. If it takes say 45 PSI to make up for the elevation, then you add another 20-30 PSI to the pressure the pump must build, to make up for friction loss and actually get some water into the upper tank. This is about what I am guessing, which is why I keep saying you will need a 60/80 pressures switch and a pump that can do a max pressure of at least 90 PSI.