Have an old well (2"PVC) that I want to use for irrigation. Water static level at 65 feet. Using a packer jet with q 1HP jet pump. Instructions say to use 1.25" down pipe. When I couple the sections of down pipe together the coupling almost fills the 2" PVC casing. Leaves maybe an 1/8" clearance. Is this enough room for the packer jet to operate? Seems like I should be using 1" down pipe instead