DSW... next time ,try adding some more sacrificial electrode to your E-tank. Think, up to, or more, equal surface area(pretty much line of sight). Yes, pressure washing right out of the tank seems to work best, when fresh out of the tank, but a solvent sprayer with water on the end of your air hose will work in a pinch. Wire wheel works well too. And, that clean piece will re-rust immediately , I normally spritz it with phosphoric acid to protect it. Dave