AA130FIREMAN - from the way you have your setup in your avatar, I'm sure you'll find a way to straighten everything out. Not much knowledge here, but are there any dissimilar metals coming into play? I repaired some old galvanized steel plumbing once, with new copper pipe; and it seemed to get worse. Galvanic action or something. I saw a system for automobiles once, it was supposed to prevent rust and corrosion by keeping a small current flowing through the vehicle. Not sure of the science, but it repels electrons or something.
I've put muriatic acid in my truck cooling system in the past, to try and dissolve buildup. Get it circulating and let it sit for a while, then flush it all out.
I put Draino crystals in my brother's old house kitchen drain once, and the drain downstairs was so weak it ate through it hahhahaha more than I bargained for. I have chinese plastic ball valves on the 1" hdpe water line coming into this place. They seem so cheap and flimsy but have held up fine for a few years. When I attach hdpe line to any barbed connection, I soften it with a heat gun and clamp it quickly to ensure a good seal.
Excellent photo of the inside of that pipe by the way