Use the FloJak Slide Calculator to Estimate the Ideal Pump Kit Length for Your Well. There are two inputs...Static Water Level and Well Depth. The Ideal Length for your system is somewhere in between...but as close to the bottom as can afford.
FloJak Hand Well Pump System Calculator
Note: The “Estimate” above is in 50 foot increments (just like out kits). It is advisable to install your pump so that the foot-valve (water inlet end) is as far below static as possible to protect from draught and seasonal water table fluctuation. Doing so will also provide additional water reserve in the well while drawing from deeper, cleaner water sources. Stay 10 to 20 feet off the bottom to avoid pumping silt.