3″ Poly WireHog Well Casing Brush, Well Cleaning Brush Well Casing Diameter or Screen Diameter 3″ casing & 3″ PS screen 4″ telescope screens As much as 90% of mineral or bacterial debris (iron bacteria or slime) may be on the inside of the well casing or screen. You can physically remove most of this debris prior to a “Unicid” chemical treatment by wire brushing the screen only for mineral scale or brushing from the static level to the bottom of the well for bacterial debris. Airlifting debris from the very bottom of the well is CRITICAL. This is a single operation with the WireHog casing brushes.