I must replace a Peabody Barnes 1/2 hp jet pump . I am getting confused as to which type pump I need . The water line is at 65' (I have no idea how deep it is) . My check valve is above ground about 1 foot in front of the pump . I need 12-15 GPM . My question is do I have to have a deep well jet or can I use a shallow well jet which offers more volume .